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  • 301.
    Babucci, Melike
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Meira, Debora M.
    Argonne Natl Lab, APS Spect Grp, Lemont, IL 60439 USA..
    Wallin, Erik
    Solibro Res AB, S-75651 Uppsala, Sweden..
    Keller, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Donzel-Gargand, Olivier
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Platzer Björkman, Charlotte
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Martin, Natalia M.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Depth-Dependent Atomic-Scale Structural Changes in (Ag,Cu)(In,Ga)Se2 Absorbers Relevant for Thin-Film Solar Cells2023In: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 6, no 18, p. 9264-9275Article in journal (Refereed)
    Abstract [en]

    Alloying a Cu(In,Ga)Se-2 (CIGS) solar cell absorber with silver to form (Ag,Cu)(In,Ga)Se-2 (ACIGS) is an effective route for improving the performance of CIGS-based thin-film solar cells by increasing the optical band gap and open-circuit voltage. While the role of Ag on the solar cell's performance and crystal structure has been analyzed, important gaps in our understanding remain, especially regarding the atomistic (short-range) structure. Previous X-ray absorption spectroscopy (XAS) results have shown that local atomic arrangements in Ag-free CIGS deviate from the long-range crystallographic structure deduced from X-ray diffraction (XRD). However, it is unclear how these structural deviations evolve with Ag alloying, particularly in the presence of Ga depth gradient. In this work, we employ angle-resolved XAS to probe the local environment of Se atoms within different depths of ACIGS absorbers with varying Ag content and Ga depth gradient. By complementing XAS results with X-ray diffraction measurements for long-range structures, glow discharge optical emission spectroscopy for elemental profiles, and scanning transmission electron microscopy for morphologies, changes in element-specific bond lengths, cell parameters, and anion displacement depending on compositions of Group [I] (Cu, Ag) and Group [III] (In, Ga) elements were mapped. The results suggest that the local atomic arrangement of the investigated ACIGS thin-film solar cell samples is depth-dependent and deviates from the long-range crystallographic structure. Possible reasons include tetragonal distortion or the presence of other phases or off-stoichiometry compounds. For the sample with the highest Ag content, increased bond lengths of Se-Group [I] atoms and Se-Ga are observed from the absorber bulk toward the near-absorber/buffer interface, whereas, in Ag-free CIGS, no significant changes are found. Results further indicate nonlinear anion displacement with Ag addition in the absorber bulk or with depth composition variation, which is likely to affect the electronic properties of solar cells. These findings offer a better understanding of the atomic-scale properties of ACIGS absorbers in actual thin-film solar cells containing in-depth composition variations.

  • 302. Baburin, Igor A
    et al.
    Klechikov, Alexey
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Mercier, Guillaume
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Talyzin, Alexandr
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Seifert, Gotthard
    Hydrogen adsorption by perforated graphene2015In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 40, no 20, p. 6594-6599Article in journal (Refereed)
    Abstract [en]

    We performed a combined theoretical and experimental study of hydrogen adsorption in graphene systems with defect-induced additional porosity. It is demonstrated that perforation of graphene sheets results in increase of theoretically possible surface areas beyond the limits of ideal defect-free graphene (∼2700 m2/g) with the values approaching ∼5000 m2/g. This in turn implies promising hydrogen storage capacities up to 6.5 wt% at 77 K, estimated from classical Grand canonical Monte Carlo simulations. Hydrogen sorption was studied for the samples of defected graphene with surface area of ∼2900 m2/g prepared using exfoliation of graphite oxide followed by KOH activation. The BET surface area of studied samples thus exceeded the value of single-layered graphene. Hydrogen uptake measured at 77 K and 296 K amounts to 5.5 wt% (30 bar) and to 0.89 wt% (120 bar), respectively. 

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  • 303.
    Backes, Claudia
    et al.
    Heidelberg Univ, Germany; Trinity Coll Dublin, Ireland; Trinity Coll Dublin, Ireland.
    Abdelkader, Amr M.
    Univ Cambridge, England.
    Alonso, Concepcion
    Autonomous Univ Madrid, Spain.
    Andrieux-Ledier, Amandine
    Univ Paris Saclay, France.
    Arenal, Raul
    ARAID Fundat, Spain; Univ Zaragoza, Spain; Univ Zaragoza, Spain.
    Azpeitia, Jon
    CSIC, Spain.
    Balakrishnan, Nilanthy
    Univ Nottingham, England.
    Banszerus, Luca
    Rhein Westfal TH Aachen, Germany; Rhein Westfal TH Aachen, Germany.
    Barjon, Julien
    Univ Paris Saclay, France.
    Bartali, Ruben
    Fdn Bruno Kessler, Italy.
    Bellani, Sebastiano
    Ist Italiano Tecnol, Italy.
    Berger, Claire
    Univ Grenoble Alpes, France; Georgia Inst Technol, GA 30332 USA.
    Berger, Reinhard
    Tech Univ Dresden, Germany; Tech Univ Dresden, Germany.
    Ortega, M. M. Bernal
    Politecn Torino, Italy.
    Bernard, Carlo
    Univ Zurich, Switzerland.
    Beton, Peter H.
    Univ Nottingham, England.
    Beyer, Andre
    Bielefeld Univ, Germany.
    Bianco, Alberto
    Univ Strasbourg, France.
    Boggild, Peter
    Tech Univ Denmark, Denmark.
    Bonaccorso, Francesco
    Ist Italiano Tecnol, Italy; BeDimens Spa, Italy.
    Barin, Gabriela Borin
    Empa, Switzerland.
    Botas, Cristina
    CIC EnergiGUNE, Spain.
    Bueno, Rebeca A.
    CSIC, Spain.
    Carriazo, Daniel
    CIC EnergiGUNE, Spain; Basque Fdn Sci, Spain.
    Castellanos-Gomez, Andres
    CSIC, Spain.
    Christian, Meganne
    CNR, Italy.
    Ciesielski, Artur
    Univ Strasbourg, France.
    Ciuk, Tymoteusz
    Inst Technol Mat Elekt, Poland.
    Cole, Matthew T.
    Dept Elect and Elect Engn, England.
    Coleman, Jonathan
    Trinity Coll Dublin, Ireland; Trinity Coll Dublin, Ireland.
    Coletti, Camilla
    Ist Italiano Tecnol, Italy; Ist Italiano Tecnol, Italy.
    Crema, Luigi
    Fdn Bruno Kessler, Italy.
    Cun, Huanyao
    Univ Zurich, Switzerland.
    Dasler, Daniela
    Friedrich Alexander Univ Erlangen Nurnberg, Germany; Friedrich Alexander Univ Erlangen Nurnberg, Germany.
    De Fazio, Domenico
    Univ Cambridge, England.
    Diez, Noel
    CIC EnergiGUNE, Spain.
    Drieschner, Simon
    Univ Munich, Germany.
    Duesberg, Georg S.
    Univ Bundeswehr Munchen, Germany.
    Fasel, Roman
    Empa, Switzerland; Univ Bern, Switzerland.
    Feng, Xinliang
    Tech Univ Dresden, Germany; Tech Univ Dresden, Germany.
    Fina, Alberto
    Politecn Torino, Italy.
    Forti, Stiven
    Ist Italiano Tecnol, Italy.
    Galiotis, Costas
    Univ Patras, Greece; Fdn Res and Technol Hellas FORTH ICE HT, Greece.
    Garberoglio, Giovanni
    European Ctr Theoret Studies Nucl Phys and Related, Italy; INFN, Italy.
    Garcia, Jorge M.
    CSIC, Spain.
    Antonio Garrido, Jose
    Inst Catalan Nanotecnol ICN2, Spain.
    Gibertini, Marco
    Ecole Polytech Fed Lausanne, Switzerland; Ecole Polytech Fed Lausanne, Switzerland.
    Goelzhaeuser, Armin
    Bielefeld Univ, Germany.
    Gomez, Julio
    Avanzare Innovac Tecnol SL, Spain.
    Greber, Thomas
    Univ Zurich, Switzerland.
    Hauke, Frank
    Friedrich Alexander Univ Erlangen Nurnberg, Germany; Friedrich Alexander Univ Erlangen Nurnberg, Germany.
    Hemmi, Adrian
    Univ Zurich, Switzerland.
    Hernandez-Rodriguez, Irene
    CSIC, Spain.
    Hirsch, Andreas
    Friedrich Alexander Univ Erlangen Nurnberg, Germany; Friedrich Alexander Univ Erlangen Nurnberg, Germany.
    Hodge, Stephen A.
    Univ Cambridge, England.
    Huttel, Yves
    CSIC, Spain.
    Jepsen, Peter U.
    Tech Univ Denmark, Denmark.
    Jimenez, Ignacio
    CSIC, Spain.
    Kaiser, Ute
    Univ Ulm, Germany.
    Kaplas, Tommi
    Univ Eastern Finland, Finland.
    Kim, HoKwon
    Ecole Polytech Fed Lausanne, Switzerland; Ecole Polytech Fed Lausanne, Switzerland.
    Kis, Andras
    Ecole Polytech Fed Lausanne, Switzerland; Ecole Polytech Fed Lausanne, Switzerland.
    Papagelis, Konstantinos
    Fdn Res and Technol Hellas FORTH ICE HT, Greece; Aristotle Univ Thessaloniki, Greece.
    Kostarelos, Kostas
    Univ Manchester, England.
    Krajewska, Aleksandra
    Inst Technol Mat Elekt, Poland; Polish Acad Sci, Poland.
    Lee, Kangho
    Univ Bundeswehr Munchen, Germany.
    Li, Changfeng
    Aalto Univ, Finland.
    Lipsanen, Harri
    Aalto Univ, Finland.
    Liscio, Andrea
    CNR, Italy.
    Lohe, Martin R.
    Tech Univ Dresden, Germany; Tech Univ Dresden, Germany.
    Loiseau, Annick
    Univ Paris Saclay, France.
    Lombardi, Lucia
    Univ Cambridge, England.
    Francisca Lopez, Maria
    CSIC, Spain.
    Martin, Oliver
    Friedrich Alexander Univ Erlangen Nurnberg, Germany; Friedrich Alexander Univ Erlangen Nurnberg, Germany.
    Martin, Cristina
    Univ Castilla La Mancha, Spain.
    Martinez, Lidia
    CSIC, Spain.
    Angel Martin-Gago, Jose
    CSIC, Spain.
    Ignacio Martinez, Jose
    CSIC, Spain.
    Marzari, Nicola
    Ecole Polytech Fed Lausanne, Switzerland; Ecole Polytech Fed Lausanne, Switzerland.
    Mayoral, Alvaro
    Univ Zaragoza, Spain; ShanghaiTech Univ, Peoples R China.
    McManus, John
    Trinity Coll Dublin, Ireland; Trinity Coll Dublin, Ireland.
    Melucci, Manuela
    CNR, Italy.
    Mendez, Javier
    CSIC, Spain.
    Merino, Cesar
    Grp Antolin Ingn SA, Spain.
    Merino, Pablo
    CSIC, Spain; CSIC, Spain.
    Meyer, Andreas P.
    Friedrich Alexander Univ Erlangen Nurnberg, Germany; Friedrich Alexander Univ Erlangen Nurnberg, Germany.
    Miniussi, Elisa
    Univ Zurich, Switzerland.
    Miseikis, Vaidotas
    Ist Italiano Tecnol, Italy.
    Mishra, Neeraj
    Ist Italiano Tecnol, Italy.
    Morandi, Vittorio
    CNR, Italy.
    Munuera, Carmen
    CSIC, Spain.
    Munoz, Roberto
    CSIC, Spain.
    Nolan, Hugo
    Trinity Coll Dublin, Ireland; Trinity Coll Dublin, Ireland.
    Ortolani, Luca
    CNR, Italy.
    Ott, Anna K.
    Univ Cambridge, England; Univ Exeter, England.
    Palacio, Irene
    CSIC, Spain.
    Palermo, Vincenzo
    CNR, Italy; Chalmers Univ Technol, Sweden.
    Parthenios, John
    Fdn Res and Technol Hellas FORTH ICE HT, Greece.
    Pasternak, Iwona
    Inst Technol Mat Elekt, Poland; Warsaw Univ Technol, Poland.
    Patane, Amalia
    Univ Nottingham, England.
    Prato, Maurizio
    Basque Fdn Sci, Spain; CIC BiomaGUNE, Spain; Univ Trieste, Italy.
    Prevost, Henri
    Univ Paris Saclay, France.
    Prudkovskiy, Vladimir
    Univ Grenoble Alpes, France.
    Pugno, Nicola
    Univ Trento, Italy; Edoardo Amaldi Foudat, Italy; Queen Mary Univ London, England.
    Rojo, Teofilo
    CIC EnergiGUNE, Spain; Univ Basque Country, Spain.
    Rossi, Antonio
    Ist Italiano Tecnol, Italy.
    Ruffieux, Pascal
    Empa, Switzerland.
    Samori, Paolo
    Univ Strasbourg, France.
    Schue, Leonard
    Univ Paris Saclay, France.
    Setijadi, Eki
    Fdn Bruno Kessler, Italy.
    Seyller, Thomas
    Tech Univ Chemnitz, Germany.
    Speranza, Giorgio
    Fdn Bruno Kessler, Italy.
    Stampfer, Christoph
    Rhein Westfal TH Aachen, Germany; Rhein Westfal TH Aachen, Germany.
    Stenger, Ingrid
    Univ Paris Saclay, France.
    Strupinski, Wlodek
    Inst Technol Mat Elekt, Poland; Warsaw Univ Technol, Poland.
    Svirko, Yuri
    Univ Eastern Finland, Finland.
    Taioli, Simone
    European Ctr Theoret Studies Nucl Phys and Related, Italy; INFN, Italy; Charles Univ Prague, Czech Republic.
    Teo, Kenneth B. K.
    Buckingway Business Pk, England.
    Testi, Matteo
    Fdn Bruno Kessler, Italy.
    Tomarchio, Flavia
    Univ Cambridge, England.
    Tortello, Mauro
    Politecn Torino, Italy.
    Treossi, Emanuele
    CNR, Italy.
    Turchanin, Andrey
    Friedrich Schiller Univ Jena, Germany.
    Vazquez, Ester
    Univ Castilla La Mancha, Spain.
    Villaro, Elvira
    Interquimica, Spain.
    Whelan, Patrick R.
    Tech Univ Denmark, Denmark.
    Xia, Zhenyuan
    CNR, Italy; Chalmers Univ Technol, Sweden.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Yang, Sheng
    Tech Univ Dresden, Germany; Tech Univ Dresden, Germany.
    Yazdi, Gholamreza
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Yim, Chanyoung
    Univ Bundeswehr Munchen, Germany.
    Yoon, Duhee
    Univ Cambridge, England.
    Zhang, Xianghui
    Bielefeld Univ, Germany.
    Zhuang, Xiaodong
    Tech Univ Dresden, Germany; Tech Univ Dresden, Germany.
    Colombo, Luigi
    Univ Texas Dallas, TX 75080 USA.
    Ferrari, Andrea C.
    Univ Cambridge, England.
    Garcia-Hernandez, Mar
    CSIC, Spain.
    Production and processing of graphene and related materials2020In: Current Opinion in Chemical Engineering, E-ISSN 2211-3398, Vol. 7, no 2, article id 022001Article, review/survey (Refereed)
    Abstract [en]

    We present an overview of the main techniques for production and processing of graphene and related materials (GRMs), as well as the key characterization procedures. We adopt a hands-on approach, providing practical details and procedures as derived from literature as well as from the authors experience, in order to enable the reader to reproduce the results. Section I is devoted to bottom up approaches, whereby individual constituents are pieced together into more complex structures. We consider graphene nanoribbons (GNRs) produced either by solution processing or by on-surface synthesis in ultra high vacuum (UHV), as well carbon nanomembranes (CNM). Production of a variety of GNRs with tailored band gaps and edge shapes is now possible. CNMs can be tuned in terms of porosity, crystallinity and electronic behaviour. Section II covers top down techniques. These rely on breaking down of a layered precursor, in the graphene case usually natural crystals like graphite or artificially synthesized materials, such as highly oriented pyrolythic graphite, monolayers or few layers (FL) flakes. The main focus of this section is on various exfoliation techniques in a liquid media, either intercalation or liquid phase exfoliation (LPE). The choice of precursor, exfoliation method, medium as well as the control of parameters such as time or temperature are crucial. A definite choice of parameters and conditions yields a particular material with specific properties that makes it more suitable for a targeted application. We cover protocols for the graphitic precursors to graphene oxide (GO). This is an important material for a range of applications in biomedicine, energy storage, nanocomposites, etc. Hummers and modified Hummers methods are used to make GO that subsequently can be reduced to obtain reduced graphene oxide (RGO) with a variety of strategies. GO flakes are also employed to prepare three-dimensional (3d) low density structures, such as sponges, foams, hydro- or aerogels. The assembly of flakes into 3d structures can provide improved mechanical properties. Aerogels with a highly open structure, with interconnected hierarchical pores, can enhance the accessibility to the whole surface area, as relevant for a number of applications, such as energy storage. The main recipes to yield graphite intercalation compounds (GICs) are also discussed. GICs are suitable precursors for covalent functionalization of graphene, but can also be used for the synthesis of uncharged graphene in solution. Degradation of the molecules intercalated in GICs can be triggered by high temperature treatment or microwave irradiation, creating a gas pressure surge in graphite and exfoliation. Electrochemical exfoliation by applying a voltage in an electrolyte to a graphite electrode can be tuned by varying precursors, electrolytes and potential. Graphite electrodes can be either negatively or positively intercalated to obtain GICs that are subsequently exfoliated. We also discuss the materials that can be amenable to exfoliation, by employing a theoretical data-mining approach. The exfoliation of LMs usually results in a heterogeneous dispersion of flakes with different lateral size and thickness. This is a critical bottleneck for applications, and hinders the full exploitation of GRMs produced by solution processing. The establishment of procedures to control the morphological properties of exfoliated GRMs, which also need to be industrially scalable, is one of the key needs. Section III deals with the processing of flakes. (Ultra)centrifugation techniques have thus far been the most investigated to sort GRMs following ultrasonication, shear mixing, ball milling, microfluidization, and wet-jet milling. It allows sorting by size and thickness. Inks formulated from GRM dispersions can be printed using a number of processes, from inkjet to screen printing. Each technique has specific rheological requirements, as well as geometrical constraints. The solvent choice is critical, not only for the GRM stability, but also in terms of optimizing printing on different substrates, such as glass, Si, plastic, paper, etc, all with different surface energies. Chemical modifications of such substrates is also a key step. Sections IV-VII are devoted to the growth of GRMs on various substrates and their processing after growth to place them on the surface of choice for specific applications. The substrate for graphene growth is a key determinant of the nature and quality of the resultant film. The lattice mismatch between graphene and substrate influences the resulting crystallinity. Growth on insulators, such as SiO2, typically results in films with small crystallites, whereas growth on the close-packed surfaces of metals yields highly crystalline films. Section IV outlines the growth of graphene on SiC substrates. This satisfies the requirements for electronic applications, with well-defined graphene-substrate interface, low trapped impurities and no need for transfer. It also allows graphene structures and devices to be measured directly on the growth substrate. The flatness of the substrate results in graphene with minimal strain and ripples on large areas, allowing spectroscopies and surface science to be performed. We also discuss the surface engineering by intercalation of the resulting graphene, its integration with Si-wafers and the production of nanostructures with the desired shape, with no need for patterning. Section V deals with chemical vapour deposition (CVD) onto various transition metals and on insulators. Growth on Ni results in graphitized polycrystalline films. While the thickness of these films can be optimized by controlling the deposition parameters, such as the type of hydrocarbon precursor and temperature, it is difficult to attain single layer graphene (SLG) across large areas, owing to the simultaneous nucleation/growth and solution/precipitation mechanisms. The differing characteristics of polycrystalline Ni films facilitate the growth of graphitic layers at different rates, resulting in regions with differing numbers of graphitic layers. High-quality films can be grown on Cu. Cu is available in a variety of shapes and forms, such as foils, bulks, foams, thin films on other materials and powders, making it attractive for industrial production of large area graphene films. The push to use CVD graphene in applications has also triggered a research line for the direct growth on insulators. The quality of the resulting films is lower than possible to date on metals, but enough, in terms of transmittance and resistivity, for many applications as described in section V. Transfer technologies are the focus of section VI. CVD synthesis of graphene on metals and bottom up molecular approaches require SLG to be transferred to the final target substrates. To have technological impact, the advances in production of high-quality large-area CVD graphene must be commensurate with those on transfer and placement on the final substrates. This is a prerequisite for most applications, such as touch panels, anticorrosion coatings, transparent electrodes and gas sensors etc. New strategies have improved the transferred graphene quality, making CVD graphene a feasible option for CMOS foundries. Methods based on complete etching of the metal substrate in suitable etchants, typically iron chloride, ammonium persulfate, or hydrogen chloride although reliable, are time- and resource-consuming, with damage to graphene and production of metal and etchant residues. Electrochemical delamination in a low-concentration aqueous solution is an alternative. In this case metallic substrates can be reused. Dry transfer is less detrimental for the SLG quality, enabling a deterministic transfer. There is a large range of layered materials (LMs) beyond graphite. Only few of them have been already exfoliated and fully characterized. Section VII deals with the growth of some of these materials. Amongst them, h-BN, transition metal tri- and di-chalcogenides are of paramount importance. The growth of h-BN is at present considered essential for the development of graphene in (opto) electronic applications, as h-BN is ideal as capping layer or substrate. The interesting optical and electronic properties of TMDs also require the development of scalable methods for their production. Large scale growth using chemical/physical vapour deposition or thermal assisted conversion has been thus far limited to a small set, such as h-BN or some TMDs. Heterostructures could also be directly grown. Section VIII discusses advances in GRM functionalization. A broad range of organic molecules can be anchored to the sp(2) basal plane by reductive functionalization. Negatively charged graphene can be prepared in liquid phase (e.g. via intercalation chemistry or electrochemically) and can react with electrophiles. This can be achieved both in dispersion or on substrate. The functional groups of GO can be further derivatized. Graphene can also be noncovalently functionalized, in particular with polycyclic aromatic hydrocarbons that assemble on the sp(2) carbon network by pi-pi stacking. In the liquid phase, this can enhance the colloidal stability of SLG/FLG. Approaches to achieve noncovalent on-substrate functionalization are also discussed, which can chemically dope graphene. Research efforts to derivatize CNMs are also summarized, as well as novel routes to selectively address defect sites. In dispersion, edges are the most dominant defects and can be covalently modified. This enhances colloidal stability without modifying the graphene basal plane. Basal plane point defects can also be modified, passivated and healed in ultra-high vacuum. The decoration of graphene with metal nanoparticles (NPs) has also received considerable attention, as it allows to exploit synergistic effects between NPs and graphene. Decoration can be either achieved chemically or in the gas phase. All LMs, can be functionalized and we summarize emerging approaches to covalently and noncovalently functionalize MoS2 both in the liquid and on substrate. Section IX describes some of the most popular characterization techniques, ranging from optical detection to the measurement of the electronic structure. Microscopies play an important role, although macroscopic techniques are also used for the measurement of the properties of these materials and their devices. Raman spectroscopy is paramount for GRMs, while PL is more adequate for non-graphene LMs (see section IX.2). Liquid based methods result in flakes with different thicknesses and dimensions. The qualification of size and thickness can be achieved using imaging techniques, like scanning probe microscopy (SPM) or transmission electron microscopy (TEM) or spectroscopic techniques. Optical microscopy enables the detection of flakes on suitable surfaces as well as the measurement of optical properties. Characterization of exfoliated materials is essential to improve the GRM metrology for applications and quality control. For grown GRMs, SPM can be used to probe morphological properties, as well as to study growth mechanisms and quality of transfer. More generally, SPM combined with smart measurement protocols in various modes allows one to get obtain information on mechanical properties, surface potential, work functions, electrical properties, or effectiveness of functionalization. Some of the techniques described are suitable for in situ characterization, and can be hosted within the growth chambers. If the diagnosis is made ex situ, consideration should be given to the preparation of the samples to avoid contamination. Occasionally cleaning methods have to be used prior to measurement.

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  • 304.
    Backholm, Jonas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Georén, Peter
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Determination of solid phase chemical diffusion coefficient and density of states by electrochemical methods: Application to iridium oxide-based thin films2008In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 103, no 2, p. 023702-Article in journal (Refereed)
    Abstract [en]

    Potentiostatic intermittent titration technique (PITT) and electrochemical impedance spectroscopy (EIS) were investigated as methods to determine solid phase chemical diffusion coefficient (D) and electronic density of states (DOS). These techniques were then applied to iridium oxide (IrOx) and iridium-tantalum oxide (IrTaOx) thin films prepared by sputter deposition. The experiments, performed in 1M propionic acid between -0.2 and 0.8 V vs Ag/AgCl, showed effects of interfacial side reactions, whose contribution to the electrochemical response could be identified and corrected for in the case of PITT as well as EIS. It was found that D is strongly underestimated when using PITT with the common Cottrell formalism, which follows from non-negligible interfacial charge transfer and Ohmic resistances. EIS indicated an anomalous diffusion mechanism, and D was determined to be in the 10(-11)-10(-10) cm(2)/s range for IrOx and IrTaOx. Both PITT and EIS showed that the intercalated charge as a function of potential exhibits a shape that resembles the theoretical DOS of crystalline iridium oxide, especially for IrTaOx.

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    JAP_103(2008)
  • 305.
    Badal Tejedor, Maria
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. RISE.
    Interfacial and material aspects of powders with relevance to pharmaceutical tableting performance2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Tablets are the most common forms of drug administration. They are convenient to administer and easy to manufacture. However, problems associated with the adhesion of the powders to the tableting tools are common. This phenomenon is known as sticking and even though it has been well documented and studied, it remains poorly understood. The many factors that contribute to good performance of the powders make the sticking problem difficult to solve.

    The goal of this study is to establish a relationship between the properties measured at the nanoscale to the overall tablet mechanical properties, tablet performance and powder pre-processing induced modifications. By using atomic force microscopy (AFM) we aim to develop an analytical method to characterize the mechanical and adhesive properties of the pharmaceutical powders at the nanoscale. Other methodologies such as scanning electron microscopy (SEM), thermal analyses (DSC, TGA) and tablet strength test were also used. The materials used in this study are commonly used excipients, a sticky drug and magnesium stearate (MgSt). Two different approaches offered by AFM were employed: sharp tip imaging and colloidal probe force measurements. Nano-mechanical properties of the materials were evaluated with a sharp tip cantilever showing that higher adhesion correlates with higher tablet cohesion and that both are significantly affected by the presence of MgSt. AFM characterization of the particle surface mechanical properties at the nanoscale was also used to detect the crystallinity and amorphicity levels of the materials. New approaches to presenting such data considering the particle heterogeneity and to track the dynamics of surface recrystallization are revealed. Adhesive interactions between a steel sphere and sticky and non-sticky powders were performed with the colloidal probe technique. Sticky materials presented a higher adhesion against the steel surface, and reveal the mechanism of stickiness.

    This work thus contributes to the provision of predictability of the performance of formulations at an early stage of the development process.

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  • 306.
    Badal Tejedor, Maria
    et al.
    KTH.
    Nordgren, Niklas
    Schuleit, Michael
    Millqvist-Fureby, Anna
    Rutland, Mark W.
    AFM colloidal probe measurements implicate capillary condensation in punch-particle surface interactions during tabletingArticle in journal (Refereed)
  • 307.
    Badr, Hussein O.
    et al.
    Drexel Univ, PA 19104 USA.
    El-Melegy, Tarek
    Drexel Univ, PA 19104 USA.
    Carey, Michael
    Drexel Univ, PA 19104 USA.
    Natu, Varun
    Drexel Univ, PA 19104 USA.
    Hassig, Mary Q.
    Drexel Univ, PA 19104 USA.
    Johnson, Craig
    Drexel Univ, PA 19104 USA.
    Qian, Qian
    Drexel Univ, PA 19104 USA.
    Li, Christopher Y.
    Drexel Univ, PA 19104 USA.
    Kushnir, Kateryna
    Worcester Polytech Inst, MA 01609 USA.
    Colin-Ulloa, Erika
    Worcester Polytech Inst, MA 01609 USA.
    Titova, Lyubov V
    Worcester Polytech Inst, MA 01609 USA.
    Martin, Julia L.
    Worcester Polytech Inst, MA 01609 USA.
    Grimm, Ronald L.
    Worcester Polytech Inst, MA 01609 USA.
    Pai, Rahul
    Drexel Univ, PA 19104 USA.
    Kalra, Vibha
    Drexel Univ, PA 19104 USA.
    Karmakar, Avishek
    Drexel Univ, PA 19104 USA.
    Ruffino, Anthony
    Drexel Univ, PA 19104 USA.
    Masiuk, Stefan
    Drexel Univ, PA 19104 USA.
    Liang, Kun
    Tulane Univ, LA 70118 USA.
    Naguib, Michael
    Tulane Univ, LA 70118 USA.
    Wilson, Olivia
    Drexel Univ, PA 19104 USA.
    Magenau, Andrew
    Drexel Univ, PA 19104 USA.
    Montazeri, Kiana
    Drexel Univ, PA 19104 USA.
    Zhu, Yucheng
    Drexel Univ, PA 19104 USA.
    Cheng, Hao
    Drexel Univ, PA 19104 USA.
    Torita, Takeshi
    Murata Mfg Co Ltd, Japan.
    Koyanagi, Masashi
    Murata Mfg Co Ltd, Japan.
    Yanagimachi, Akimaro
    Murata Mfg Co Ltd, Japan.
    Ouisse, Thierry
    Univ Grenoble Alpes, France.
    Barbier, Maxime
    Univ Grenoble Alpes, France; European Synchrotron Radiat Facil ESRF, France.
    Wilhelm, Fabrice
    European Synchrotron Radiat Facil ESRF, France.
    Rogalev, Andrei
    European Synchrotron Radiat Facil ESRF, France.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hu, Yong-Jie
    Drexel Univ, PA 19104 USA.
    Barsoum, Michel
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Drexel Univ, PA 19104 USA.
    Bottom-up, scalable synthesis of anatase nanofilament-based two-dimensional titanium carbo-oxide flakes2022In: Materials Today, ISSN 1369-7021, E-ISSN 1873-4103, Vol. 54Article in journal (Refereed)
    Abstract [en]

    Two-dimensional (2D) materials offer advantages that their 3D counterparts do not. The conventional method for the bulk synthesis of 2D materials has predominantly been through etching layered solids. Herein, we convert - through a bottom-up approach - 10 binary and ternary titanium carbides, nitrides, borides, phosphides, and silicides into 2D flakes by immersing them in a tetramethylammonium hydroxide solution at temperatures in the 25-85 degrees C range. Based on X-ray diffraction, density functional theory, X-ray photoelectron, electron energy loss, Raman, X-ray absorption near edge structure spectroscopies, transmission and scanning electron microscope images and selected area diffraction, we conclude that the resulting flakes are carbon containing anatase-based layers that are, in turn, comprised of approximate to 6 x 10 angstrom(2) nanofilaments in cross-section some of which are few microns long. Electrodes made from some of these films performed well in lithium-ion and lithium-sulphur systems. These materials also reduce the viability of cancer cells thus showing potential in biomedical applications. Synthesizing 2D materials, at near ambient conditions, with non-layered, inexpensive, green precursors (e.g., TiC) is paradigm shifting and will undoubtedly open new and exciting avenues of research and applications.

  • 308.
    Badria, Adel
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. Univ Patras, Dept Mech Engn & Aeronaut, Div Appl Mech Technol Mat & Biomech, Patras, Greece..
    Koutsoukos, Petros G.
    Univ Patras, Dept Chem Engn, Patras Univ Campus, Patras 26504, Greece..
    Mavrilas, Dimosthenis
    Univ Patras, Dept Mech Engn & Aeronaut, Div Appl Mech Technol Mat & Biomech, Patras, Greece..
    Decellularized tissue-engineered heart valves calcification: what do animal and clinical studies tell us?2020In: Journal of materials science. Materials in medicine, ISSN 0957-4530, E-ISSN 1573-4838, Vol. 31, no 12, article id 132Article in journal (Refereed)
    Abstract [en]

    Cardiovascular diseases are the first cause of death worldwide. Among different heart malfunctions, heart valve failure due to calcification is still a challenging problem. While drug-dependent treatment for the early stage calcification could slow down its progression, heart valve replacement is inevitable in the late stages. Currently, heart valve replacements involve mainly two types of substitutes: mechanical and biological heart valves. Despite their significant advantages in restoring the cardiac function, both types of valves suffered from serious drawbacks in the long term. On the one hand, the mechanical one showed non-physiological hemodynamics and the need for the chronic anticoagulation therapy. On the other hand, the biological one showed stenosis and/or regurgitation due to calcification. Nowadays, new promising heart valve substitutes have emerged, known as decellularized tissue-engineered heart valves (dTEHV). Decellularized tissues of different types have been widely tested in bioprosthetic and tissue-engineered valves because of their superior biomechanics, biocompatibility, and biomimetic material composition. Such advantages allow successful cell attachment, growth and function leading finally to a living regenerative valvular tissue in vivo. Yet, there are no comprehensive studies that are covering the performance of dTEHV scaffolds in terms of their efficiency for the calcification problem. In this review article, we sought to answer the question of whether decellularized heart valves calcify or not. Also, which factors make them calcify and which ones lower and/or prevent their calcification. In addition, the review discussed the possible mechanisms for dTEHV calcification in comparison to the calcification in the native and bioprosthetic heart valves. For this purpose, we did a retrospective study for all the published work of decellularized heart valves. Only animal and clinical studies were included in this review. Those animal and clinical studies were further subcategorized into 4 categories for each depending on the effect of decellularization on calcification. Due to the complex nature of calcification in heart valves, other in vitro and in silico studies were not included. Finally, we compared the different results and summed up all the solid findings of whether decellularized heart valves calcify or not. Based on our review, the selection of the proper heart valve tissue sources (no immunological provoking residues), decellularization technique (no damaged exposed residues of the decellularized tissues, no remnants of dead cells, no remnants of decellularizing agents) and implantation techniques (avoiding suturing during the surgical implantation) could provide a perfect anticalcification potential even without in vitro cell seeding or additional scaffold treatment. [GRAPHICS] .

  • 309.
    Bae, Kichang
    et al.
    Pukyong Natl Univ, Dept Met Engn, Busan 48513, South Korea..
    Shin, Dongmin
    Pukyong Natl Univ, Dept Met Engn, Busan 48513, South Korea..
    Lee, Jonghun
    Pukyong Natl Univ, Dept Met Engn, Busan 48513, South Korea..
    Kim, Seohan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Lee, Wookjin
    Pusan Natl Univ, Sch Mat Sci & Engn, Busan 46241, South Korea..
    Jo, Ilguk
    Dong Eui Univ, Adv Mat Engn, Busan 47340, South Korea..
    Lee, Junghoon
    Pukyong Natl Univ, Dept Met Engn, Busan 48513, South Korea..
    Corrosion Resistance of Laser Powder Bed Fused AISI 316L Stainless Steel and Effect of Direct Annealing2022In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 15, no 18, article id 6336Article in journal (Refereed)
    Abstract [en]

    Alloy parts produced by an additive manufacturing method with rapid heat transfer from fast melting and solidification have different microstructures, characteristics, and performances compared with materials made by the conventional process. In this study, the corrosion and oxidation resistance of SS316L, which was prepared by the powder bed fusion process, was compared with those of cold-rolled SS316L. Additionally, the surface oxide film on stainless steel was thoroughly assessed since the film has the greatest influence on the corrosion and oxidation resistance. The effect of heat treatment on corrosion and oxidation resistance of SS316L fabricated by additive manufacturing was investigated. The SS316L has a microstructure formed by sub-grain cells, in which locally concentrated alloying elements form a stable passive film. As a result, it has a higher level of corrosion resistance and oxidation resistance than conventional cold-rolled materials. However, it was confirmed that the sub-grain cell was removed by heat treatment, which resulted in the degradation of corrosion and oxidation resistance.

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  • 310.
    Baghaei, Behnaz
    et al.
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Berglin, Lena
    University of Borås, Swedish School of Textiles.
    Hybrid natural fibre reinforcements and prepregs for thermoplastic composites with improved performance and properties2014Conference paper (Other academic)
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  • 311.
    Baginski, Maciej
    et al.
    Univ Warsaw, Fac Chem, PL-02093 Warsaw, Poland..
    Pedrazo-Tardajos, Adrian
    Univ Antwerp, Electron Microscopy Mat Res, B-2020 Antwerp, Belgium..
    Altantzis, Thomas
    Univ Antwerp, Electron Microscopy Mat Res, B-2020 Antwerp, Belgium..
    Tupikowska, Martyna
    Univ Warsaw, Fac Chem, PL-02093 Warsaw, Poland..
    Vetter, Andreas
    Karlsruhe Inst Technol, Inst Theoret Solid State Phys, D-76131 Karlsruhe, Germany..
    Tomczyk, Ewelina
    Univ Warsaw, Fac Chem, PL-02093 Warsaw, Poland..
    Suryadharma, Radius N. S.
    Karlsruhe Inst Technol, Inst Theoret Solid State Phys, D-76131 Karlsruhe, Germany..
    Pawlak, Mateusz
    Univ Warsaw, Fac Chem, PL-02093 Warsaw, Poland..
    Andruszkiewicz, Aneta
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Univ Warsaw, Fac Chem, PL-02093 Warsaw, Poland..
    Gorecka, Ewa
    Univ Warsaw, Fac Chem, PL-02093 Warsaw, Poland..
    Pociecha, Damian
    Univ Warsaw, Fac Chem, PL-02093 Warsaw, Poland..
    Rockstuhl, Carsten
    Karlsruhe Inst Technol, Inst Theoret Solid State Phys, D-76131 Karlsruhe, Germany.;Karlsruhe Inst Technol, Inst Nanotechnol, D-76131 Karlsruhe, Germany..
    Bals, Sara
    Univ Antwerp, Electron Microscopy Mat Res, B-2020 Antwerp, Belgium..
    Lewandowski, Wiktor
    Univ Warsaw, Fac Chem, PL-02093 Warsaw, Poland..
    Understanding and Controlling the Crystallization Process in Reconfigurable Plasmonic Superlattices2021In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 15, no 3, p. 4916-4926Article in journal (Refereed)
    Abstract [en]

    The crystallization of nanomaterials is a primary source of solid-state, photonic structures. Thus, a detailed understanding of this process is of paramount importance for the successful application of photonic nanomaterials in emerging optoelectronic technologies. While colloidal crystallization has been thoroughly studied, for example, with advanced in situ electron microscopy methods, the noncolloidal crystallization (freezing) of nanoparticles (NPs) remains so far unexplored. To fill this gap, in this work, we present proof-of-principle experiments decoding a crystallization of reconfigurable assemblies of NPs at a solid state. The chosen material corresponds to an excellent testing bed, as it enables both in situ and ex situ investigation using X-ray diffraction ( XRD), transmission electron microscopy (TEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), atomic force microscopy (AFM), and optical spectroscopy in visible and ultraviolet range (UV-vis) techniques. In particular, ensemble measurements with small-angle XRD highlighted the dependence of the correlation length in the NPs assemblies on the number of heating/cooling cycles and the rate of cooling. Ex situ TEM imaging further supported these results by revealing a dependence of domain size and structure on the sample preparation route and by showing we can control the domain size over 2 orders of magnitude. The application of HAADF-STEM tomography, combined with in situ thermal control, provided three-dimensional single-particle level information on the positional order evolution within assemblies. This combination of real and reciprocal space provides insightful information on the anisotropic, reversibly reconfigurable assemblies of NPs. TEM measurements also highlighted the importance of interfaces in the polydomain structure of nanoparticle solids, allowing us to understand experimentally observed differences in UV-vis extinction spectra of the differently prepared crystallites. Overall, the obtained results show that the combination of in situ heating HAADF-STEM tomography with XRD and ex situ TEM techniques is a powerful approach to study nanoparticle freezing processes and to reveal the crucial impact of disorder in the solid-state aggregates of NPs on their plasmonic properties.

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  • 312. BAGNALL, ANDREW
    Molecular engineering of electrocatalytic nanomaterials for hydrogen evolution based on a cobalt tetraazamacrocyclic catalystManuscript (preprint) (Other academic)
  • 313.
    Bagnall, Andrew J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Novel electrode and photoelectrode materials for hydrogen production based on molecular catalysts2022Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The PhD project focussed on the application of a cobalt tetraazamacrocyclic complex, in the literature commonly referred to as [Co(CR)Cl2]+ as a molecular catalyst for the hydrogen evolution reaction (HER). This was within the broader scope of the EU MSCA H2020 ITN ‘eSCALED’ project, which primarily aimed to create artificial leaf devices for the storage of solar energy in chemical fuels and, as part of this, sought the development of novel bio-inspired and scalable materials. This included researching molecular catalysts without platinum group metals (PGMs) currently relied upon in commercial technology.

    Three main projects were pursued: firstly, studies of the mechanism of the catalyst itself under organic electrocatalytic conditions. Catalytic intermediates were generated and identified using spectroscopy (UV-vis, NMR, EPR) and the catalytic behaviour was followed with electrochemical techniques. An ECEC mechanism with a rate-determining second protonation step associated with the release of H2 was identified, noting in particular an initial protonation step on the macrocycle at the Co(II) state that was hypothesised to involve the macrocycle amine group acting as a proton relay under the investigated conditions.

    Secondly, a new synthetic strategy towards novel derivatives of [Co(CR)Cl2]+ was developed to prepare a derivative for anchoring onto sp2-carbon surfaces by pi-stacking interactions. The immobilised catalyst was studied by electrochemical methods and compared with another derivative from collaborators at ICIQ, showing that both derivatives work as heterogenised electrocatalysts for the HER with high faradaic efficiencies and good stability over one hour at pH 2 and especially pH 7, but one derivative displays higher current densities and stability, invoking some consideration of rational design principles for modifying molecular catalysts.

    Thirdly, studies of a photocatalytic system made up of copper indium sulfide quantum dots (CuInS2 QDs) as a photosensitiser with either [Co(CR)Cl2]+ or its benzoic acid-functionalised derivative were carried out in ascorbate buffer, focussing on the photocatalytic performance and electron transfer (ET) processes between the CuInS2 QDs and the catalyst to explain the remarkable activity and robustness reported for closely related systems. CuInS2 QDs modified to have a ‘hybrid-passivation’ ligand system for compatibility with NiO films were used. Rapid QD-catalyst ET processes were noted for both catalysts. A static binding model with a strong binding equilibrium was adapted for the system,  applying a Poisson distribution. This prompts a reconsideration of the importance of anchoring groups for QD-catalyst ET efficiency in solution.

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  • 314.
    Bahr, A.
    et al.
    TU Wien, Christian Doppler Lab Surface Engn high performanc, A-1060 Vienna, Austria..
    Glechner, T.
    TU Wien, Christian Doppler Lab Surface Engn high performanc, A-1060 Vienna, Austria..
    Grimmer, A.
    TU Wien, Christian Doppler Lab Surface Engn high performanc, A-1060 Vienna, Austria..
    Wojcik, T.
    TU Wien, Christian Doppler Lab Surface Engn high performanc, A-1060 Vienna, Austria..
    Kutrowatz, P.
    TU Wien, Christian Doppler Lab Surface Engn high performanc, A-1060 Vienna, Austria..
    Podsednik, M.
    TU Wien, Inst Chem Technol & Analyt, A-1060 Vienna, Austria..
    Limbeck, A.
    TU Wien, Inst Chem Technol & Analyt, A-1060 Vienna, Austria..
    Heller, M.
    Friedrich Alexander Univ Erlangen Nurnberg, Dept Mat Sci, D-91058 Erlangen, Germany..
    Ramm, J.
    Oerlikon Surface Solut AG, Oerlikon Balzers, FL-9496 Balzers, Liechtenstein..
    Hunold, O.
    Oerlikon Surface Solut AG, Oerlikon Balzers, FL-9496 Balzers, Liechtenstein..
    Kolozsvari, S.
    Friedrich Alexander Univ Erlangen Nurnberg, Dept Mat Sci, D-91058 Erlangen, Germany..
    Polcik, P.
    Plansee Composite Mat GmbH, D-86983 Lechbruck, Germany..
    Ntemou, Eleni
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Primetzhofer, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Felfer, P.
    Friedrich Alexander Univ Erlangen Nurnberg, Dept Mat Sci, D-91058 Erlangen, Germany..
    Riedl, H.
    TU Wien, Christian Doppler Lab Surface Engn high performanc, A-1060 Vienna, Austria.;TU Wien, Inst Mat Sci & Technol, A-1060 Vienna, Austria..
    High-temperature oxidation resistance of ternary and quaternary Cr-(Mo)-Si-B2-z coatings-Influence of Mo addition2023In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 468, article id 129733Article in journal (Refereed)
    Abstract [en]

    The Si-based alloying of transition metal diborides is a promising strategy to improve their limited oxidation resistance in high-temperature environments. In this study, we investigate the oxidation resistance of ternary and quaternary Cr-(Mo)-Si-B2-z coatings sputter-deposited from alloyed CrB2/TMSi2 targets (TM = Cr, Mo). The asdeposited Cr-(Mo)-Si-B2-z coatings are stabilized in the single-phased hexagonal AlB2-structure, except the high-Si containing Cr0.26Mo0.11Si0.24B0.39 presenting amorphous character. The Mo-containing Cr-Mo-Si-B2-z films exhibit relatively high hardness compared to their ternary Cr-Si-B2-z counterparts, obtaining up to 26 GPa due to the formation of (Cr,Mo)B-2 solid solutions. The Si-alloying in ternary and quaternary coatings provides oxidation resistance up to 1200 degrees C, owing to the formation of highly protective double-layered scales consisting of SiO2 with a Cr2O3 layer on top, inhibiting oxygen inward diffusion. The quaternary Cr0.31Mo0.07Si0.15B0.47 coating is distinguished by superior oxidation resistance with lower porosity and void formation compared to the ternary Cr0.37Si0.16B0.47. Mo proved to be the key element for the higher stability and enhanced oxidation resistance due to the evolution of the MoSi2 phase at similar to 600 degrees C. This phase formation controls the Si diffusion and mobility within the microstructure, thus reducing the porosity and governing the Si supply to form SiO2 scale. The quaternary Cr0.31Mo0.07Si0.15B0.47 coating maintained an oxidation resistance up to 30 h at 1200 degrees C by forming a 2.5 mu m dense amorphous Si-based oxide scale with a thin Cr2O3 on top.

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  • 315.
    Bahr, A.
    et al.
    TU Wien, Christian Doppler Lab Surface Engn High performanc, Vienna, Austria..
    Glechner, T.
    TU Wien, Christian Doppler Lab Surface Engn High performanc, Vienna, Austria..
    Wojcik, T.
    TU Wien, Christian Doppler Lab Surface Engn High performanc, Vienna, Austria..
    Kirnbauer, A.
    TU Wien, Inst Mat Sci & Technol, Vienna, Austria..
    Sauer, M.
    TU Wien, Analyt Instrumentat Ctr, Vienna, Austria..
    Foelske, A.
    TU Wien, Analyt Instrumentat Ctr, Vienna, Austria..
    Hunold, O.
    Oerlikon Balzers, Oerlikon Surface Solut AG, Balzers, Liechtenstein..
    Ramm, J.
    Oerlikon Balzers, Oerlikon Surface Solut AG, Balzers, Liechtenstein..
    Kolozsvari, S.
    Plansee Composite Mat GmbH, Lechbruck, Germany..
    Ntemou, Eleni
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Pitthan, Eduardo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Primetzhofer, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Riedl, H.
    TU Wien, Christian Doppler Lab Surface Engn High performanc, Vienna, Austria.;TU Wien, Inst Mat Sci & Technol, Vienna, Austria..
    Hahn, R.
    TU Wien, Christian Doppler Lab Surface Engn High performanc, Vienna, Austria..
    Non-reactive HiPIMS deposition of NbCx thin films: Effect of the target power density on structure-mechanical properties2022In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 444, article id 128674Article in journal (Refereed)
    Abstract [en]

    The exceptional mechanical properties of transition metal carbide coatings are known to be governed by the carbon content and its morphological distribution. Here, we verify the influence of the target peak power density on the chemical composition, microstructure, and mechanical properties of NbCx coatings grown by non-reactive high-power impulse magnetron sputtering (HiPIMS). By tuning the pulse parameters, the power density can be increased from 0.11 to 1.48 kW/cm2 leading to a decrease in the C/Nb ratio from 1.52 to 0.99 within the films - proven by combined elastic backscattering and time-of-flight elastic recoil detection analysis. This decrease in the C/Nb ratio is accompanied by microstructural changes from nanocomposite morphologies with an average grain size of 6.6 +/- 2.5 nm at 0.13 kW/cm2 into more columnar structures with an average column width of 65.2 +/- 18.7 nm at 1.48 kW/cm2. Independent from the C/Nb ratio, all films exhibit a single face-centered cubic structure. The mechanical properties correlate with the enhanced growth behavior dominated by ions at higher peak power densities and the varied C/Nb ratios. A maximum in hardness and fracture toughness of H = 38.7 +/- 3.6 GPa and KIc = 2.78 +/- 0.13 MPa center dot m1/2 (at 3.2 GPa residual compressive stress), is obtained for the nearly stoichiometric NbC coating exhibiting C/Nb ratio of 1.06.

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  • 316.
    Bahr, Ahmed
    et al.
    TU Wien, Christian Doppler Lab Surface Engn High Performan, Vienna, Austria..
    Beck, Oskar
    TU Wien, Christian Doppler Lab Surface Engn High Performan, Vienna, Austria..
    Glechner, Thomas
    TU Wien, Christian Doppler Lab Surface Engn High Performan, Vienna, Austria..
    Grimmer, Alexander
    TU Wien, Christian Doppler Lab Surface Engn High Performan, Vienna, Austria..
    Wojcik, Tomasz
    TU Wien, Christian Doppler Lab Surface Engn High Performan, Vienna, Austria..
    Kutrowatz, Philip
    TU Wien, Christian Doppler Lab Surface Engn High Performan, Vienna, Austria..
    Ramm, Juergen
    Oerlikon Surface Solut AG, Oerlikon Balzers, Balzers, Liechtenstein..
    Hunold, Oliver
    Oerlikon Surface Solut AG, Oerlikon Balzers, Balzers, Liechtenstein..
    Kolozsvari, Szilard
    Plansee Composite Mat GmbH, Lechbruck, Germany..
    Polcik, Peter
    Plansee Composite Mat GmbH, Lechbruck, Germany..
    Ntemou, Eleni
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Primetzhofer, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Riedl, Helmut
    TU Wien, Christian Doppler Lab Surface Engn High Performan, Vienna, Austria.;TU Wien, Inst Mat Sci & Technol, Vienna, Austria. TU Wien, Christian Doppler Lab Surface Engn High Performan, A-1060 Vienna, Austria..
    Quaternary diborides-improving the oxidation resistance of TiB2 +/- z coatings by disilicide alloying2023In: Materials Research Letters, E-ISSN 2166-3831, Vol. 11, no 9, p. 733-741Article in journal (Refereed)
    Abstract [en]

    To overcome the limited oxidation resistance of the emerging class of transition metal borides, we suggest within this study novel quaternary diborides, Ti-TM-Si-B-2 +/- z (TM = Ta, Mo), achieving the compromise between excellent oxidation resistance and requirements of hard coatings. Single-phase AlB2-type structured Ti-TM-Si-B-2 +/- z films (3-5 mu m) are sputter-deposited from TiB2/TMSi2 targets. The Ti-Ta-Si-B-2 +/- z coatings exhibit 36 GPa in hardness, while maintaining strongly retarded oxidation kinetics till 1000 degrees C. Ti-Mo-Si-B-2 +/- z coatings preserve a hardness up to 27 GPa, although outperforming all their counterparts by featuring outstanding oxidation resistance with 440nm oxide scale thickness after 1 h at 1200 degrees C. First report on quaternary Ti-TM-Si-B-2 +/- z coatings stabilized in hexagonal AlB2-prototype structures. These hard coating materials exhibit unprecedented oxidation resistance up to 1200 degrees C due to the formation of Si-rich scales.

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  • 317.
    Bai, Jianhao
    et al.
    National University of Singapore.
    Beyer, Sebastian
    National University of Singapore.
    Mak, Wing Cheung
    Hong Kong University of Science and Technology, Hong Kong, China .
    Trau, Dieter
    National University of Singapore.
    Fabrication of inflated LbL microcapsules with a ‘bead-in-a-capsule’ morphology2009In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 5, p. 4152-4160Article in journal (Refereed)
    Abstract [en]

    The fabrication of inflated Layer-by-Layer (LbL) microcapsules with a unique ‘bead-in-a-capsule’ morphology is presented. Currently, the fabrication of LbL microcapsules using conventional aqueous LbL techniques usually results in microcapsules with a two-phase system (LbL capsular wall with an air, liquid, solid or hydrogel core). Here, we present the fabrication of inflated LbL microcapsules with a unique three-phase system (LbL capsular wall, hydrogel microbead in an aqueous core) by using the Reverse-Phase LbL (RP-LbL) technique. The RP-LbL technique is performed in an organic solvent and allows encapsulation of water-soluble templates and molecules with high efficiency. Firstly, the RP-LbL technique is used to coat polymer layers onto agarose microbeads containing TRIS buffer for the formation of LbL capsular walls onto the microbeads and to minimize out-diffusion of encapsulated TRIS. Next, the polymer-coated agarose microbeads are transferred from an organic to an aqueous solvent where the TRIS molecules induce an osmotic pressure in the microcapsules' interior. This pressure drives the inflation of the LbL microcapsules that causes the expansion of the LbL capsular walls. Fluorescence staining reveals that the inflated LbL microcapsules consist of an agarose microbead suspended within the aqueous interior of the capsule but still attached to the LbL capsular wall at one point; thereby displaying a ‘bead-in-a-capsule’ morphology. It was demonstrated that the degree of inflation depends on the concentration of pre-loaded TRIS and the number of coated polymer layers. Also, ADOGEN® 464 (a cationic surfactant) is required for the fabrication of the inflated LbL microcapsules. The mass of dextran macromolecules (65–2000 kDa) diffusing through the LbL capsular wall had decreased by at least 49% after expansion of the capsular wall. Inflated microcapsules were shown to be capable of controlling the distribution of two different materials internally. Hence, it is possible that inflated microcapsules can permit localized control over chemical or enzymatic reactions for future uses in biomedical applications.

  • 318.
    Bai, Sai
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Yuan, Zhongcheng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Colloidal metal halide perovskite nanocrystals: synthesis, characterization, and applications2016In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 4, no 18, p. 3898-3904Article in journal (Refereed)
    Abstract [en]

    Colloidal metal halide perovskite nanocrystals (NCs) have emerged as promising materials for optoelectronic devices and received considerable attention recently. Their superior photoluminescence (PL) properties provide significant advantages for lighting and display applications. In this Highlight, we discuss recent developments in the design and chemical synthesis of colloidal perovskite NCs, including both organic-inorganic hybrid and all inorganic perovskite NCs. We review the excellent PL properties and current optoelectronic applications of these perovskite NCs. In addition, critical challenges that currently limit the applicability of perovskite NCs are discussed, and prospects for future directions are proposed.

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  • 319.
    Bairagi, Samiran
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Järrendahl, Kenneth
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hsiao, Ching-Lien
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Glancing Angle Deposition and Growth Mechanism of Inclined AlN Nanostructures Using Reactive Magnetron Sputtering2020In: Coatings, ISSN 2079-6412, Vol. 10, no 8, article id 768Article in journal (Refereed)
    Abstract [en]

    Glancing angle deposition (GLAD) of AlN nanostructures was performed at room temperature by reactive magnetron sputtering in a mixed gas atmosphere of Ar and N-2. The growth behavior of nanostructures shows strong dependence on the total working pressure and angle of incoming flux. In GLAD configuration, the morphology changed from coalesced, vertical nanocolumns with faceted terminations to highly inclined, fan-like, layered nanostructures (up to 38 degrees); while column lengths decreased from around 1743 to 1068 nm with decreasing pressure from 10 to 1.5 mTorr, respectively. This indicates a change in the dominant growth mechanism from ambient flux dependent deposition to directional ballistic shadowing deposition with decreasing working pressures, which is associated with the change of energy and incident angle of incoming reactive species. These results were corroborated using simulation of metal transport (SiMTra) simulations performed at similar working pressures using Ar and N separately, which showed the average particle energy and average angle of incidence decreased while the total average scattering angle of the metal flux arriving at substrate increased with increasing working pressures. Observing the crystalline orientation of GLAD deposited wurtzite AlN nanocolumns using X-ray diffraction (XRD), pole-figure measurements revealedc-axis growth towards the direction of incoming flux and a transition from fiber-like to biaxial texture took place with increasing working pressures. Under normal deposition conditions, AlN layer morphology changed from {0001} to {10 (1) over bar1} with increasing working pressure because of kinetic energy-driven growth.

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  • 320.
    Baird, Ross
    et al.
    Heriot Watt Univ, Inst Mech Proc & Energy Engn, Sch Engn & Phys Sci, Edinburgh EH14 4AS, Scotland..
    Chang, Ribooga
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Nanotechnology and Functional Materials.
    Cheung, Ocean
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Nanotechnology and Functional Materials.
    Sanna, Aimaro
    Heriot Watt Univ, Inst Mech Proc & Energy Engn, Sch Engn & Phys Sci, Edinburgh EH14 4AS, Scotland..
    High Temperature CO2 Capture Performance and Kinetic Analysis of Novel Potassium Stannate2023In: International Journal of Molecular Sciences, ISSN 1661-6596, E-ISSN 1422-0067, Vol. 24, no 3, article id 2321Article in journal (Refereed)
    Abstract [en]

    For the first time, the use of stannate-based sorbents was investigated as high temperature CO2 sorption to evaluate their potential to contribute towards reducing carbon emissions. The sorption capacity and kinetics of commercial tin oxide, sodium, potassium and calcium stannates and lab synthesised potassium stannates were tested using thermogravimetric analysis. Commercial K2SnO3 was found to possess the largest CO2 uptake capacity (2.77 mmol CO2/g or 12.2 wt%) at 700 °C, which is among the highest for potassium sorbents, but the CO2 desorption was not successful. On the contrary, the in-house synthesised K-stannate (K-B) using facile solid-state synthesis outperformed the other sorbents, resulting in a CO2 uptake of 7.3 wt% after 5 min, an adsorption rate (0.016 mg/s) one order of magnitude higher than the other stannates, and stability after 40 cycles. The XRD and XPS analyses showed that K-B contains a mixture of K2SnO3 (76%) and K4SnO4 (21%), while the Scherrer crystal sizes confirmed good resistance to sintering for the potassium stannates. Among the apparent kinetic model tested, the pseudo-second order model was the most suitable to predict the CO2 sorption process of K-B, indicating that chemical adsorption is dominant, while film-diffusion resistance and intra-particle diffusion resistance governed the sorption process in K-B. In summary, this work shows that solid-state synthesised potassium stannate could be an effective sorbent for high temperature separation, and additional work is required to further elucidate its potential.

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  • 321.
    Bakare, Fatimat
    et al.
    University of Borås, School of Engineering.
    Åkesson, Dan
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Bashir, Tariq
    University of Borås, School of Engineering.
    Ingman, Petri
    Srivastava, Rajiv
    Synthesis and characterization of unsaturated lactic acid based thermoset bio-resins2014In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 67, p. 570-582Article in journal (Refereed)
    Abstract [en]

    Bio-based thermoset resins have been synthesized using lactic acid oligomers, which were functionalized with carbon–carbon double bonds, in order to allow their crosslinking by a free radical mechanism. Two different resin structures were synthesized. One resin was composed of an allyl alcohol terminated lactic acid oligomer, which was end-functionalized with methacrylic anhydride (MLA resin). The second resin was a mixture of the same allyl alcohol-lactic acid oligomer, and penthaerythritol. This mixture was end-functionalized with methacrylic anhydride, in order to get a methacrylate functionalized lactic acid oligomer, and methacrylate functionalized penthaerythritol (PMLA resin). The synthesized resins were characterized using FT-IR, 1H NMR and 13C NMR spectroscopy, differential scanning calorimetry as well as dynamic mechanical analysis to confirm the resin structure and reactivity. The flow viscosities were also measured in order to evaluate the suitability of the resins to be used as a matrix in composite applications. The results showed that the PMLA resin has better mechanical, thermal and rheological properties than the MLA resin, and both had properties which were comparable with a commercial unsaturated polyester resin. The high biobased content of 90% and the high glass transition temperature at 100 °C for the PMLA resin makes it an attractive candidate for composite applications where crude oil based unsaturated polyester resins are normally used.

  • 322.
    Bakhit, Babak
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Multifunctional Transition-metal Diboride Coatings Synthesized by Magnetron sputtering with Synchronized Metal-ion Irradiation2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Refractory transition-metal diborides (TMB2), classified as ultra-high temperature ceramics, are promising materials for extreme thermal and chemical environments. There is a growing demand for employing TMB2 in high-temperature electrodes, advanced nuclear fission reactors, molten metal containment, refractory crucibles, thermocouple protection tubes in steel baths and aluminum reduction cells, reinforcement fibers, solar power, aerospace, and armor applications. Magnetron-sputter-deposited TMB2 have recently received increasing attention as the next class of hard ceramic protective thin films. These layers usually crystallize in a hexagonal AlB2 crystal structure (P6/mmm, SG-191) in which B atoms form graphite-like honeycomb sheets between hexagonal-close-packed TM layers. The strong covalent bonding between TM and B atoms as well as within the honeycomb B sheets provides high melting temperature, hardness, and stiffness, while metallic bonding within TM layers results in good electrical and thermal conductivities. However, sputter-deposited TMB2 films suffer from several critical issues such as boron overstoichiometry, high brittleness, and low oxidation resistance. All of these aspects are addressed in the thesis.

    In Paper 1, the common issue with sputter-deposited diboride thin films, i.e. the presence of excess B, is resolved by using high power impulse magnetron sputtering (HiPIMS). The B/Ti ratio in TiBx films, used as a model materials system, is controllably varied from 2.08 to 1.83 by adjusting the HiPIMS pulse length ton, while maintaining the average power and pulse frequency constant. As a result, the peak current density increases from 0.27 to 0.88 A/cm2, which leads to an increased gas rarefaction and, hence, higher metal-ion densities in the plasma. Film growth becomes then increasingly controlled by ionized target atoms, rather than neutral species. Since sputter-ejected Ti atoms have a higher probability of being ionized than B atoms, due to their lower first-ionization potential and larger ionization cross-section, the B/Ti ratio in the films decreases a function of target peak current.

    While TM diborides are inherently hard, that alone is not sufficient to prevent failure in applications involving high stresses, as hardness is typically accompanied by brittleness. In order to avoid brittle cracking, thin films must be both hard and relatively ductile, which is referred to as high toughness. In Paper 2, it is demonstrated that Zr1-xTaxBy thin films grown by hybrid high-power impulse and DC magnetron co-sputtering (Ta-HiPIMS/ZrB2-DCMS) with x ≥ 0.2 are not only hard, but also tough. The films with x ≥ 0.2 show a self-organized columnar core/shell nanostructure (see Paper 3), in which crystalline hexagonal Zr-rich stoichiometric Zr1-xTaxB2 cores are surrounded by narrow dense, disordered Ta-rich shells that are B-deficient.

    The disordered shells have the structural characteristics of metallic-glass thin films, which exhibit both high strength and toughness. Hence, such a nanostructure combines the benefits of crystalline diboride nanocolumns, providing the high hardness, with the dense metallic-glasslike shells, which give rise to enhanced toughness.

    The mechanical properties of Zr1-xTaxBy thin films annealed in Ar atmosphere are studied as a function of annealing temperature Ta up to 1200 °C in Paper 4. In-situ and ex-situ nanoindentation analyses reveal that all films undergo age hardening up to Ta = 800 °C, with the highest hardness achieved for Zr0.8Ta0.2B1.8 (45.5±1.0 GPa). The age hardening, which occurs without any phase separation or decomposition, can be explained by point-defect recovery that enhances chemical bond density. Although hardness decreases at Ta > 800 °C due mainly to recrystallization, column coarsening, and planar defect annihilation, all layers show hardness values above 34 GPa over the entire Ta range.

    The oxidation resistance of TiBx thin films is addressed in Paper 5. In general, TMB2 suffer from rapid high-temperature oxidation, which is a critical issue for many applications. In this study, it is demonstrated that alloying the films with Al significantly increases the oxidation resistance with only a slight decrease in hardness. Contrary to bulk TiB2 synthesized by powder metallurgy processes, the oxidation products of TiB2 thin films do not contain the B2O3 oxide scale, which is usually observed below 1000 °C in air, and merely consists of a TiO2 phase. The enhanced oxidation resistance is attributed to the formation of a dense, protective Al-containing oxide scale, which considerably decreases the oxygen diffusion rate by suppressing the oxidecrystallites coarsening.

    To realize the goal of fully multifunctional diborides, Zr1-xCrxBy thin films grown by hybrid Cr-HiPIMS/ZrB2-DCMS co-sputtering are studied in Paper 6. These layers exhibit a unique combination of high hardness, toughness, wear, oxidation, and corrosion resistance.

    The last paper (Paper 7) addresses the issue of efficient energy and resource consumption in industrial processes, which United Nations defines as one of the sustainable development goals. The idea here is to replace the conventionally used thermal-energy flux from resistive heaters with the irradiation by high mass metal ions (Hf+), which results in more efficient energy transfer to the deposited layer. We deposited Ti0.67Hf0.33B1.7 films using hybrid HfB2-HiPIMS/TiB2-DCMS co-sputtering at substrate temperature not exceeding 100 °C. Results reveal that dense layers can be achieved with high hardness values (> 40 GPa) even though no external substrate heating was used during the process.

  • 323.
    Bakhit, Babak
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Palisaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Thörnberg, Jimmy
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Petrov, Ivan
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Univ Illinois, IL 61801 USA; Natl Taiwan Univ Sci & Technol, Taiwan.
    Greene, Joseph E
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Univ Illinois, IL 61801 USA; Natl Taiwan Univ Sci & Technol, Taiwan.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Improving the high-temperature oxidation resistance of TiB2 thin films by alloying with Al2020In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 196, p. 677-689Article in journal (Refereed)
    Abstract [en]

    Refractory transition-metal diborides (TMB2) are candidates for extreme environments due to melting points above 3000 degrees C, excellent hardness, good chemical stability, and thermal and electrical conductivity. However, they typically suffer from rapid high-temperature oxidation. Here, we study the effect of Al addition on the oxidation properties of sputter-deposited TiB2-rich Ti1-xAlxBy thin films and demonstrate that alloying the films with Al significantly increases the oxidation resistance with a slight decrease in hardness. TiB2.4 layers are deposited by dc magnetron sputtering (DCMS) from a TiB2 target, while Ti1-xAlxBy alloy films are grown by hybrid high-power impulse and dc magnetron co-sputtering (Al-HiPIMS/TiB2-DCMS). All as-deposited films exhibit columnar structure. The column boundaries of TiB2.4 are B-rich, while Ti0.68Al0.32B1.35 alloys have Ti-rich columns surrounded by a Ti(1-x)Al(x)By tissue phase which is predominantly Al rich. Air-annealing TiB2.4 at temperatures above 500 degrees C leads to the formation of oxide scales that do not contain B and mostly consist of a rutile-TiO2 (s) phase. The resulting oxidation products are highly porous due to the evaporation of B2O3 (g) phase as well as the coarsening of TiO2 crystallites. This poor oxidation resistance is significantly improved by alloying with Al. While air-annealing at 800 degrees C for 0.5 h results in the formation of an similar to 1900-nm oxide scale on TiB2.4, the thickness of the scale formed on the Ti0.68Al0.32B1.35 alloys is similar to 470 nm. The enhanced oxidation resistance is attributed to the formation of a dense, protective Al-containing oxide scale that considerably decreases the oxygen diffusion rate by suppressing the oxide-crystallites coarsening. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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  • 324.
    Bakhit, Babak
    et al.
    Linköping Univ, Dept Phys IFM, Thin Film Phys Div, SE-58183 Linköping, Sweden..
    Primetzhofer, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Pitthan, Eduardo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sortica, Mauricio A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Ntemou, Eleni
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Rosen, Johanna
    Linköping Univ, Dept Phys IFM, Thin Film Phys Div, SE-58183 Linköping, Sweden..
    Hultman, Lars
    Linköping Univ, Dept Phys IFM, Thin Film Phys Div, SE-58183 Linköping, Sweden..
    Petrov, Ivan
    Linköping Univ, Dept Phys IFM, Thin Film Phys Div, SE-58183 Linköping, Sweden.;Univ Illinois, Mat Res Lab, Urbana, IL 61801 USA.;Univ Illinois, Dept Mat Sci, Urbana, IL 61801 USA.;Natl Taiwan Univ Sci & Technol, Dept Mat Sci & Engn, Taipei 10607, Taiwan..
    Greczynski, Grzegorz
    Linköping Univ, Dept Phys IFM, Thin Film Phys Div, SE-58183 Linköping, Sweden..
    Systematic compositional analysis of sputter-deposited boron-containing thin films2021In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 39, no 6, article id 063408Article in journal (Refereed)
    Abstract [en]

    Boron-containing materials exhibit a unique combination of ceramic and metallic properties that are sensitively dependent on their given chemical bonding and elemental compositions. However, determining the composition, let alone bonding, with sufficient accuracy is cumbersome with respect to boron, being a light element that bonds in various coordinations. Here, we report on the comprehensive compositional analysis of transition-metal diboride (TMBx) thin films (TM = Ti, Zr, and Hf) by energy-dispersive x-ray spectroscopy (EDX), x-ray photoelectron spectroscopy (XPS), time-of-flight elastic recoil detection analysis (ToF-ERDA), Rutherford backscattering spectrometry (RBS), and nuclear reaction analysis (NRA). The films are grown on Si and C substrates by dc magnetron sputtering from stoichiometric TMB2 targets and have hexagonal AlB2-type columnar structures. EDX considerably overestimates B/TM ratios, x, compared to the other techniques, particularly for ZrBx. The B concentrations obtained by XPS strongly depend on the energy of Ar+ ions used for removing surface oxides and contaminants prior to analyses and are more reliable for 0.5 keV Ar+. ToF-ERDA, RBS, and NRA yield consistent compositions in TiBx. They also prove TiBx and ZrBx films to be homogeneous with comparable B/TM ratios for each film. However, ToF-ERDA, employing a 36-MeV I-127(8+) beam, exhibits challenges in depth resolution and quantification of HfBx due to plural and multiple scattering and associated energy loss straggling effects. Compared to ToF-ERDA, RBS (for the film grown on C substrates) and NRA provide more reliable B/Hf ratios. Overall, a combination of methods is recommended for accurately pinpointing the compositions of borides that contain heavy transition metals.

  • 325.
    Bakhit, Babak
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Primetzhofer, Daniel
    Uppsala University, Sweden.
    Pitthan, Eduardo
    Uppsala University, Sweden.
    Sortica, Mauricio A.
    Uppsala University, Sweden.
    Ntemou, Eleni
    Uppsala University, Sweden.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Petrov, Ivan
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. University of Illinois, USA; National Taiwan University of Science and Technology, Taiwan.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Systematic compositional analysis of sputter-deposited boron-containing thin films2021In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 39, no 6, article id 063408Article in journal (Refereed)
    Abstract [en]

    Boron-containing materials exhibit a unique combination of ceramic and metallic properties that are sensitively dependent on their given chemical bonding and elemental compositions. However, determining the composition, let alone bonding, with sufficient accuracy is cumbersome with respect to boron, being a light element that bonds in various coordinations. Here, we report on the comprehensive compositional analysis of transition-metal diboride (TMBx) thin films (TM = Ti, Zr, and Hf) by energy-dispersive x-ray spectroscopy (EDX), x-ray photoelectron spectroscopy (XPS), time-of-flight elastic recoil detection analysis (ToF-ERDA), Rutherford backscattering spectrometry (RBS), and nuclear reaction analysis (NRA). The films are grown on Si and C substrates by dc magnetron sputtering from stoichiometric TMB2 targets and have hexagonal AlB2-type columnar structures. EDX considerably overestimates B/TM ratios, x, compared to the other techniques, particularly for ZrBx. The B concentrations obtained by XPS strongly depend on the energy of Ar+ ions used for removing surface oxides and contaminants prior to analyses and are more reliable for 0.5 keV Ar+. ToF-ERDA, RBS, and NRA yield consistent compositions in TiBx. They also prove TiBx and ZrBx films to be homogeneous with comparable B/TM ratios for each film. However, ToF-ERDA, employing a 36-MeV 127I8+ beam, exhibits challenges in depth resolution and quantification of HfBx due to plural and multiple scattering and associated energy loss straggling effects. Compared to ToF-ERDA, RBS (for the film grown on C substrates) and NRA provide more reliable B/Hf ratios. Overall, a combination of methods is recommended for accurately pinpointing the compositions of borides that contain heavy transition metals.

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  • 326.
    Bala, Sukhen
    et al.
    School of Chemical Science, Indian Association for the Cultivation of Science, Kolkata, India; Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, Sun Yat-Sen University, Guangzhou, P. R. China.
    De, Avik
    School of Chemical Science, Indian Association for the Cultivation of Science, Kolkata, India.
    Adhikary, Amit
    School of Chemical Science, Indian Association for the Cultivation of Science, Kolkata, West Bengal, India.
    Saha, Sayan
    School of Chemical Science, Indian Association for the Cultivation of Science, Kolkata, India.
    Akhtar, Sohel
    School of Chemical Science, Indian Association for the Cultivation of Science, Kolkata, India.
    Das, Krishna Sundar
    School of Chemical Science, Indian Association for the Cultivation of Science, Kolkata, India.
    Tong, Ming-Liang
    Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, Sun Yat-Sen University, Guangzhou, P. R. China.
    Mondal, Raju
    School of Chemical Science, Indian Association for the Cultivation of Science, Kolkata, India.
    Influence of Semirigidity and Diverse Binding Modes of an Asymmetric Pyridine-pyrazole Based Bis-Chelating Ligand in Controlling Molecular Architectures and Their Properties2020In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 20, no 9, p. 5698-5708Article in journal (Refereed)
  • 327.
    Balamurugan, Chandran
    et al.
    Gwangju Inst Sci & Technol GIST, South Korea; Wonkwang Univ, South Korea.
    Cho, Kyusang
    Gwangju Inst Sci & Technol GIST, South Korea.
    Park, Byoungwook
    Korea Res Inst Chem Technol, South Korea.
    Kim, Jehan
    Pohang Univ Sci & Technol, South Korea.
    Kim, Nara
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Pak, Yusin
    Korea Inst Sci & Technol KIST, South Korea.
    Kong, Jaemin
    Gyeongsang Natl Univ, South Korea.
    Kwon, Sooncheol
    Gwangju Inst Sci & Technol GIST, South Korea; Wonkwang Univ, South Korea.
    Large modulation of the chemical and electronic sensitization of TiO2/Ag/NiO nanostructure via in situ hydrothermal-induced heterointerface engineering2022In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 430, article id 132690Article in journal (Refereed)
    Abstract [en]

    Chemical and electronic sensitization in metal oxide gas sensors are severely limited by poor dimension controls of metal oxide nanostructure and their electric/electronic properties. These limitations are overcome using hydrothermal-induced heterointerface engineering approaches. This work demonstrates that forming spherical titanium dioxide nanoparticles on a substrate significantly reduce a surface energy barrier of nucleation and induces novel mesophorous hierarchical TiO2 structure during hydrothermal synthesis, consequently increasing the surface area of the structure by similar to 3 times compared to that of control. In addition, we succeeded in tailoring the energetics of hierarchical TiO2 nanosctructure by decorating with the nickel oxide and silver nanoparticles, which results in a desirable semiconductors/metal heterointerface for fast charge transfer where silver nanoparticles bridge nickel oxide and TiO2 nanostructure, and silver nanoparticles serve as preferential sites for chemisorption and migration of oxygen anions. The resulting heterostructure sensing properties such as sensitivity, limit of detection and selectivity are studied as a function of operating temperature (30-150 degrees C), relative humidity (RH) and various volatile organic analytes concentrations. The TiO2/Ag/NiO heterostructure finally exhibits a high gas response of similar to 2.1 for acetone with a limit of detection of 34 ppb at 30 degrees C (or 21 ppb at 90 degrees C), and retains an excellent selectivity of acetone even at 90 % relative humidity. It exhibited a highly stable and speedy gas response for acetone toward various gases such as formaldehyde, ethanol, hydrogen sulfide, carbon monoxide even operating at 90 degrees C. Our results suggest a potential of constructed TiO2/Ag/NiO heterostructure for superior sensing volatile organic acetone and will also stimulate research on hetero-structured gas sensors with high sensitivity and selectivity.

  • 328.
    Baljozovic, Milos
    et al.
    Paul Scherrer Inst, Lab Micro & Nanotechnol, CH-5232 Villigen, Switzerland..
    Liu, Xunshan
    Univ Bern, Dept Chem Biochem & Pharmaceut Sci, Freiestr 3, CH-3012 Bern, Switzerland..
    Popova, Olha
    Univ Basel, Dept Phys, Klingelbergstr 82, CH-4056 Basel, Switzerland..
    Girovsky, Jan
    Paul Scherrer Inst, Lab Micro & Nanotechnol, CH-5232 Villigen, Switzerland..
    Nowakowski, Jan
    Paul Scherrer Inst, Lab Micro & Nanotechnol, CH-5232 Villigen, Switzerland..
    Rossmann, Harald
    Paul Scherrer Inst, Lab Micro & Nanotechnol, CH-5232 Villigen, Switzerland..
    Nijs, Thomas
    Univ Basel, Dept Phys, Klingelbergstr 82, CH-4056 Basel, Switzerland..
    Moradi, Mina
    Paul Scherrer Inst, Lab Micro & Nanotechnol, CH-5232 Villigen, Switzerland.;Univ Appl Sci & Arts Northwestern Switzerland, Sch Life Sci, Grundenstr 40, CH-4132 Muttenz, Switzerland..
    Mousavi, S. Fatemeh
    Univ Basel, Dept Phys, Klingelbergstr 82, CH-4056 Basel, Switzerland..
    Plumb, Nicholas C.
    Paul Scherrer Inst, Swiss Light Source, CH-5232 Villigen, Switzerland..
    Radovic, Milan
    Paul Scherrer Inst, Swiss Light Source, CH-5232 Villigen, Switzerland..
    Ballav, Nirmalya
    Indian Inst Sci Educ & Res, Dept Chem, Pune 411008, Maharashtra, India..
    Dreiser, Jan
    Paul Scherrer Inst, Swiss Light Source, CH-5232 Villigen, Switzerland..
    Decurtins, Silvio
    Univ Bern, Dept Chem Biochem & Pharmaceut Sci, Freiestr 3, CH-3012 Bern, Switzerland..
    Pasti, Igor A.
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11000, Serbia.;KTH Royal Inst Technol, Sch Ind Engn & Management, Dept Mat Sci & Engn, Brinellvagen 23, S-10044 Stockholm, Sweden..
    Skorodumova, Natalia V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. KTH Royal Inst Technol, Sch Ind Engn & Management, Dept Mat Sci & Engn, Brinellvagen 23, S-10044 Stockholm, Sweden..
    Liu, Shi-Xia
    Univ Bern, Dept Chem Biochem & Pharmaceut Sci, Freiestr 3, CH-3012 Bern, Switzerland..
    Jung, Thomas A.
    Paul Scherrer Inst, Lab Micro & Nanotechnol, CH-5232 Villigen, Switzerland.;Univ Basel, Dept Phys, Klingelbergstr 82, CH-4056 Basel, Switzerland..
    Self-Assembly and Magnetic Order of Bi-Molecular 2D Spin Lattices of M(II,III) Phthalocyanines on Au(111)2021In: MAGNETOCHEMISTRY, ISSN 2312-7481, Vol. 7, no 8, article id 119Article in journal (Refereed)
    Abstract [en]

    Single layer low-dimensional materials are presently of emerging interest, including in the context of magnetism. In the present report, on-surface supramolecular architecturing was further developed and employed to create surface supported two-dimensional binary spin arrays on atomically clean non-magnetic Au(111). By chemical programming of the modules, different checkerboards were produced combining phthalocyanines containing metals of different oxidation and spin states, diamagnetic zinc, and a metal-free 'spacer'. In an in-depth, spectro-microscopy and theoretical account, we correlate the structure and the magnetic properties of these tunable systems and discuss the emergence of 2D Kondo magnetism from the spin-bearing components and via the physico-chemical bonding to the underlying substrate. The contributions of the individual elements, as well as the role of the electronic surface state in the bottom substrate, are discussed, also looking towards further in-depth investigations.

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  • 329. Ballikaya, S.
    et al.
    Oner, Y.
    Temel, T.
    Ozkal, B.
    Bailey, T. P.
    Toprak, Muhammet Sadaka
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Uher, C.
    Thermoelectric and thermal stability improvements in Nano-Cu 2 Se included Ag 2 Se2019In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 273, p. 122-127Article in journal (Refereed)
    Abstract [en]

    Recently, silver chalcogenides have attracted great attention due to their potential application for room temperature power generation and local cooling. In this work, we report the thermoelectric properties and thermal stability of bulk Ag 2 Se with nano-Cu 2 Se inclusions ((Ag 2 Se) 1-x (Cu 2 Se) x where x = 0, 0.02 and 0.05). Ag 2 Se samples were prepared via melting, annealing and the nanocomposite was prepared by ball milling this material with required amount of nano-Cu 2 Se; finally, the samples were consolidated by spark plasma sintering. High temperature and low temperature transport properties were assessed by the measurements of the Seebeck coefficient, electrical conductivity, thermal conductivity, and Hall coefficient. The phase composition and microstructure were explored by powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, while the thermal stability of samples was investigated via heating microscopy and heat capacity measurement. Room temperature PXRD and SEM indicated that two separate phases of Ag 2 Se and Cu 2 Se form in nano-Cu 2 Se included composites. Heating microscopy and the heat capacity measurement indicate that the thermal stability of Ag 2 Se is enhanced with increasing nano-Cu 2 Se inclusions. The sign of the Seebeck coefficient, in agreement with the Hall coefficient, shows that electrons are the dominant carriers in all samples. The electrical conductivity of the samples increases and the Seebeck coefficient decreases with increasing amount of the nano-Cu 2 Se inclusion, likely due to augmented carrier concentration. Despite the larger electrical conductivity, the thermal conductivity is suppressed with nano-Cu 2 Se inclusions. A high power factor and reduced thermal conductivity lead to a maximum ZT value of 0.45 at 875 K for (Ag 2 Se) 1-x (nano-Cu 2 Se) x sample where x is 0.05.

  • 330.
    Baloukas, Bill
    et al.
    Polytech Montreal, Dept Engn Phys, Montreal.
    Arvizu, Miguel A
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Wen, Rui-Tao
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Vernhes, Richard
    Polytech Montreal, Dept Engn Phys, Montreal.
    Klemberg-Sapieha, Jolanta E.
    Polytech Montreal, Dept Engn Phys, Montreal.
    Martinu, Ludvik
    Polytech Montreal, Dept Engn Phys, Montreal.
    Galvanostatic Rejuvenation of Electrochromic WO3 Thin Films: Ion Trapping and Detrapping Observed by Optical Measurements and by Time-of-Flight Secondary Ion Mass Spectrometry2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 20, p. 16996-17002Article in journal (Refereed)
    Abstract [en]

    Electrochromic (EC) smart windows are able to decrease our energy footprint while enhancing indoor comfort and convenience. However, the limited durability of these windows, as well as their cost, result in hampered market introduction. Here, we investigate thin films of the most widely studied EC material, WO3. Specifically, we combine optical measurements (using spectrophotometry in conjunction with variable-angle spectroscopic ellipsometry) with time-of-flight secondary ion mass spectrometry and atomic force microscopy. Data were taken on films in their as-deposited state, after immersion in a Li-ion-conducting electrolyte, after severe degradation by harsh voltammetric cycling and after galvanostatic rejuvenation to regain the original EC performance. Unambiguous evidence was found for the trapping and detrapping of Li ions in the films, along with a thickness increase or decrease during degradation and rejuvenation, respectively. It was discovered that (i) the trapped ions exhibited a depth gradient; (ii) following the rejuvenation procedure, a small fraction of the Li ions remained trapped in the film and gave rise to a weak short-wavelength residual absorption; and (iii) the surface roughness of the film was larger in the degraded state than in its virgin and rejuvenated states. These data provide important insights into the degradation mechanisms of EC devices and into means of achieving improved durability.

  • 331.
    Bamford, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Tool wear in turning of titanium alloy Ti–6Al–4V: Challenges and potential solutions for crater wear, diffusion and chip formation2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Titanium alloys are major materials used in the airplane industry, and prospects show that airplane production will double in the next 20 years. Consequently, the demand for cutting tools for machining of titanium alloys will increase. The primary problem when machining titanium alloys is their low thermal conductivity. Crater wear is the main factor limiting tool life, and is generally caused by thermal diffusion due to high temperatures in the tool-chip interface.

    This master’s thesis was performed in collaboration with Sandvik Coromant, with the prospect to increase knowledge of how diffusion and chip formation influences crater wear progression. The aim was to study tool wear of cutting tools when turning Ti–6Al–4V. This was done by testing two different rake face geometries, both coated and uncoated, at cutting speeds of 30–115 m/min. Diffusion was investigated to learn about the impact it has on crater wear. Chips were examined to investigate chip formation and shear strain.

    The coated modified rake face insert showed less crater wear only for the initial few seconds of machining. Uncoated inserts with a modified rake face showed higher diffusion rate and faster crater wear progression than did standard inserts. The standard inserts showed twice as long tool life as did the modified inserts. No significant differences in the chip formation mechanism were found between modified and standard inserts. Cracks were found within shear bands that were thinner than usual, which suggest that the generation of cracks allows less shear deformation.

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  • 332. Banerjee, Amitava
    et al.
    Araujo, Rafael B.
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Uppsala University, Sweden.
    Unveiling the thermodynamic and kinetic properties of NaxFe(SO4)(2) (x=0-2): toward a high-capacity and low-cost cathode material2016In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, no 46, p. 17960-17969Article in journal (Refereed)
    Abstract [en]

    The mineral eldfellite, NaFe(SO4)(2), was recently proposed as an inexpensive candidate for the next generation of cathode application in Na-based batteries. Employing the density functional theory framework, we have investigated the phase stability, electrochemical properties and ionic diffusion of this eldfellite cathode material. We showed that the crystal structure undergoes a volume shrinkage of approximate to 8% upon full removal of Na ions with no imaginary frequencies at the Gamma point of phonon dispersion. This evokes the stability of the host structure. According to this result, we proposed structural changes to get higher specific energy by inserting two Na ions per redox-active metal. Our calculations indicate NaV(SO4)(2) as the best candidate with the capability of reversibly inserting two Na ions per redox center and producing an excellent specific energy. The main bottleneck for the application of eldfellite as a cathode is the high activation energies for the Na+ ion hop, which can reach values even higher than 1 eV for the charged state. This effect produces a low ionic insertion rate.

  • 333.
    Banerjee, Amitava
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Araujo, Rafael Barros
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Sjödin, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Appl Mat Phys, Dept Mat, S-10044 Stockholm, Sweden;Royal Inst Technol KTH, Appl Mat Phys, Dept Engn, S-10044 Stockholm, Sweden.
    Identifying the tuning key of disproportionation redox reaction in terephthalate: A Li-based anode for sustainable organic batteries2018In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 47, p. 301-308Article in journal (Refereed)
    Abstract [en]

    The ever-increasing consumption of energy storage devices has pushed the scientific community to realize strategies toward organic electrodes with superior properties. This is owed to advantages such as economic viability and eco-friendliness. In this context, the family of conjugated dicarboxylates has emerged as an interesting candidate for the application as negative electrodes in advanced Li-ion batteries due to the revealed thermal stability, rate capability, high capacity and high cyclability. This work aims to rationalize the effects of small molecular modifications on the electrochemical properties of the terephthalate anode by means of first principles calculations. The crystal structure prediction of the investigated host compounds dilithium terephthalate (Li2TP) and diethyl terephthalate (Et2Li0TP) together with their crystal modification upon battery cycling enable us to calculate the potential profile of these materials. Distinct underlying mechanisms of the redox reactions were obtained where Li2TP comes with a disproportionation reaction while Et2Li0TP displays sequential redox reactions. This effect proved to be strongly correlated to the Li coordination number evolution upon the Li insertion into the host structures. Finally, the calculations of sublimation enthalpy inferred that polymerization techniques could easily be employed in Et2Li0TP as compared to Li2TP. Similar results are observed with methyl, propyl, and vinyl capped groups. That could be a strategy to enhance the properties of this compound placing it into the gallery of the new anode materials for state of art Li-batteries.

  • 334.
    Banerjee, Amitava
    et al.
    Indian Inst Technol Jodhpur, Dept Met & Mat Engn, Jodhpur 342030, Rajasthan, India..
    Khossossi, Nabil
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Luo, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics. Indian Inst Technol Ropar, Dept Phys, Rupnagar 140001, Punjab, India..
    Promise and reality of organic electrodes from materials design and charge storage perspective2022In: Journal of Materials Chemistry A, ISSN 2050-7488, E-ISSN 2050-7496, Vol. 10, no 29, p. 15215-15234Article, review/survey (Refereed)
    Abstract [en]

    Organic electrode materials are becoming increasingly important as they reduce the C-footprint as well as the production cost of currently used and studied rechargeable batteries. With increasing demand for high-energy-density devices, over the past few decades, various innovative new materials based on the fundamental structure-property relationships and molecular design have been explored to enable high-capacity next-generation battery chemistries. One critical dimension that catalyzes this study is the building up of an in-depth understanding of the structure-property relationship and mechanism of alkali ion batteries. In this review, we present a critical overview of the progress in the technical feasibility of organic battery electrodes for use in long-term and large-scale electrical energy-storage devices based on the materials designing, working mechanisms, performance, and battery safety. Specifically, we discuss the underlying alkali ion storage mechanisms in specific organic batteries, which could provide the designing requirements to overcome the limitations of organic batteries. We also discuss the promising future research directions in the field of alkali ion organic batteries, especially multivalent organic batteries along with monovalent alkali ion organic batteries.

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  • 335.
    Banin, U.
    et al.
    Hebrew Univ Jerusalem, Inst Chem, IL-91904 Jerusalem, Israel; Hebrew Univ Jerusalem, Ctr Nanosci & Nanotechnol, IL-91904 Jerusalem, Israel.
    Waiskopf, N.
    Hebrew Univ Jerusalem, Inst Chem, IL-91904 Jerusalem, Israel; Hebrew Univ Jerusalem, Ctr Nanosci & Nanotechnol, IL-91904 Jerusalem, Israel.
    Hammarström, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Freitag, Marina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Johansson, Erik M. J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Sá, Jacinto
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Tian, Haining
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Johnston, M. B.
    Univ Oxford, Dept Phys, Clarendon Lab, Pk Rd, Oxford OX1 3PU, England.
    Herz, L. M.
    Univ Oxford, Dept Phys, Clarendon Lab, Pk Rd, Oxford OX1 3PU, England.
    Milot, R. L.
    Univ Warwick, Dept Phys, Gibbet Hill Rd, Coventry CV4 7AL, W Midlands, England.
    Kanatzidis, M. G.
    Northwestern Univ, Dept Chem, Evanston, IL 60208 USA.
    Ke, W.
    Northwestern Univ, Dept Chem, Evanston, IL 60208 USA.
    Spanopoulos, I.
    Northwestern Univ, Dept Chem, Evanston, IL 60208 USA.
    Kohlstedt, K. L.
    Northwestern Univ, Dept Chem, Evanston, IL 60208 USA.
    Schatz, G. C.
    Northwestern Univ, Dept Chem, Evanston, IL 60208 USA.
    Lewis, N.
    CALTECH, Div Chem & Chem Engn, 210 Noyes Lab 127-72, Pasadena, CA 91125 USA; CALTECH, Beckman Inst, 210 Noyes Lab 127-72, Pasadena, CA 91125 USA.
    Meyer, T.
    Univ N Carolina, Dept Chem, Chapel Hill, NC USA.
    Nozik, A. J.
    Natl Renewable Energy Lab, Golden, CO USA; Univ Colorado, Dept Chem, Boulder, CO 80309 US.
    Beard, M. C.
    Natl Renewable Energy Lab, Golden, CO USA.
    Armstrong, F.
    Univ Oxford, Dept Chem, Oxford, England.
    Megarity, C. F.
    Univ Oxford, Dept Chem, Oxford, England.
    Schmuttenmaer, C. A.
    Yale Univ, Dept Chem, 225 Prospect St, New Haven, CT 06520 USA.
    Batista, V. S.
    Yale Univ, Dept Chem, 225 Prospect St, New Haven, CT 06520 USA.
    Brudvig, G. W.
    Yale Univ, Dept Chem, 225 Prospect St, New Haven, CT 06520 USA.
    Nanotechnology for catalysis and solar energy conversion2021In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 32, no 4, article id 042003Article in journal (Refereed)
    Abstract [en]

    This roadmap on Nanotechnology for Catalysis and Solar Energy Conversion focuses on the application of nanotechnology in addressing the current challenges of energy conversion: 'high efficiency, stability, safety, and the potential for low-cost/scalable manufacturing' to quote from the contributed article by Nathan Lewis. This roadmap focuses on solar-to-fuel conversion, solar water splitting, solar photovoltaics and bio-catalysis. It includes dye-sensitized solar cells (DSSCs), perovskite solar cells, and organic photovoltaics. Smart engineering of colloidal quantum materials and nanostructured electrodes will improve solar-to-fuel conversion efficiency, as described in the articles by Waiskopf and Banin and Meyer. Semiconductor nanoparticles will also improve solar energy conversion efficiency, as discussed by Boschloo et al in their article on DSSCs. Perovskite solar cells have advanced rapidly in recent years, including new ideas on 2D and 3D hybrid halide perovskites, as described by Spanopoulos et al 'Next generation' solar cells using multiple exciton generation (MEG) from hot carriers, described in the article by Nozik and Beard, could lead to remarkable improvement in photovoltaic efficiency by using quantization effects in semiconductor nanostructures (quantum dots, wires or wells). These challenges will not be met without simultaneous improvement in nanoscale characterization methods. Terahertz spectroscopy, discussed in the article by Milot et al is one example of a method that is overcoming the difficulties associated with nanoscale materials characterization by avoiding electrical contacts to nanoparticles, allowing characterization during device operation, and enabling characterization of a single nanoparticle. Besides experimental advances, computational science is also meeting the challenges of nanomaterials synthesis. The article by Kohlstedt and Schatz discusses the computational frameworks being used to predict structure-property relationships in materials and devices, including machine learning methods, with an emphasis on organic photovoltaics. The contribution by Megarity and Armstrong presents the 'electrochemical leaf' for improvements in electrochemistry and beyond. In addition, biohybrid approaches can take advantage of efficient and specific enzyme catalysts. These articles present the nanoscience and technology at the forefront of renewable energy development that will have significant benefits to society.

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  • 336. Bao, Zijia
    et al.
    Zhou, Guojun
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Liu, Xinrong
    Peng, Yuxin
    Huang, Zhehao
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zheng, Haoquan
    A bimetallic 3D interconnected metal–organic framework with 2D morphology and its derived electrocatalyst for oxygen reduction2023In: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 25, no 13, p. 1869-1873Article in journal (Refereed)
    Abstract [en]

    Metal–organic frameworks (MOFs) are widely used as precursors to generate derivatives for electrocatalysis. However, two-dimensional (2D) MOFs often suffer from the collapse of their 2D structures after being treated at high temperature. Herein, we used the dense ZIF-EC1 as a precursor and doped Co as a secondary metal. The content of Co in ZIF-EC1 can be tuned without changing the crystalline structure. After pyrolysis, the derived carbon-based material maintains the 2D morphology from the parental precursor. The derived ZIF-EC1(ZnCo)-20-900 exhibits the best activity toward the ORR, which is even better than that of Pt/C. This work demonstrates the potential of using a nonporous dense MOF as a precursor and optimizing electrocatalytic ORR activity by tuning the Co content.

  • 337.
    Barghi, Hamidreza
    University of Borås, School of Engineering.
    Functionalization of Synthetic Polymers for Membrane Bioreactors2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Membrane bioreactors (MBRs) show great promise for productivity improvement and energy conservation in conventional bioprocesses for wastewater reclamation. In order to attain high productivity in a bioprocess, it is crucial to retain the microorganisms in the bioreactors by preventing wash out. This enables recycling of the microorganisms, and is consequently saving energy. The main feature of MBRs is their permeable membranes, acting as a limitative interface between the medium and the microorganisms. Permeation of nutrients and metabolites through the membranes is thus dependent on the membrane characteristics, i.e. porosity, hydrophilicity,and polarity. The present thesis introduces membranes for MBRs to be used in a continuous feeding process, designed in the form of robust, durable, and semi-hydrophilic films that constitute an effective barrier for the microorganisms, while permitting passage of nutrients and metabolites. Polyamide 46 (polytetramethylene adipamide), a robust synthetic polymer, holds the desired capabilities, with the exception of porosity and hydrophilicity. In order to achieve adequate porosity and hydrophilicity, bulk functionalization of polyamide 46 with different reagents was performed. These procedures changed the configuration from dense planar to spherical, resulting in increased porosity. Hydroxyethylation of the changed membranes increased the surface tension from 11.2 to 44.6 mJ/m2. The enhanced hydrophilicity of PA 46 resulted in high productivity of biogas formation in a compact MBR, due to diminished biofouling. Copolymerization of hydrophilized polyamide 46 with hydroxymethyl 3,4-ethylenedioxythiophene revealed electroconductivity and hydrophilic properties, adequate for use in MBRs. To find either the maximal pH stability or the surface charge of the membranes having undergone carboxymethylation, polarity and the isoelectric point (pI) of the treated membranes were studied by means of a Zeta analyzer. The hydroxylated PA 46 was finally employed in a multilayer membrane bioreactor and compared with hydrophobic polyamide and PVDF membranes. The resulting biogas production showed that the hydroxylated PA 46 membrane was, after 18 days without regeneration, fully comparable with PVDF membranes.

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  • 338.
    Barhoum, Ahmed
    et al.
    Vrije Universiteit Brussel (VUB), Belgium.
    Samyn, Pieter
    Hasselt University, Belgium.
    Öhlund, Thomas
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Dufresne, Alain
    Univ. Grenoble Alpes, France.
    Review of recent research on flexible multifunctional nanopapers2017In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 9, no 40, p. 15181-15205Article in journal (Refereed)
    Abstract [en]

    Traditional paper and papermaking have struggled with a declining market during the last decades. However, the incorporation of nanotechnology in papermaking has brought possibilities to develop low-cost, biocompatible and flexible products with sophisticated functionalities. The functionality of nanopapers emerges from the intrinsic properties of the nanofibrous network, the additional loading of specific nanomaterials, or the additional deposition and patterning of thin films of nanomaterials on the paper surface. A successful development of functional nanopapers requires understanding in how the nanopaper matrix, nanomaterial fillers, coating pigments/inks, functional additives and manufacturing processes all interact to provide the intended functionality. This review addresses the emerging area of functional nanopapers. The review discusses flexible and multifunctional nanopapers, nanomaterials being used in nanopaper making, manufacturing techniques, and functional applications that provide new important possibilities to utilize papermaking technology. The interface where nanomaterials research meets traditional papermaking has important implications for food packaging, energy harvesting, and energy storage, flexible electronics, low-cost devices for medical diagnostics, and numerous other areas.

  • 339. Barišić, Antun
    et al.
    Lützenkirchen, Johannes
    Bebić, Nikol
    Li, Qinzhi
    Hanna, Khalil
    Shchukarev, Andrey
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Begović, Tajana
    Experimental Data Contributing to the Elusive Surface Charge of Inert Materials in Contact with Aqueous Media2021In: Colloids and interfaces, E-ISSN 2504-5377, Vol. 5, no 1, article id 6Article in journal (Other academic)
    Abstract [en]

    We studied the charging of inert surfaces (polytetrafluoroethylene, i.e., PTFE; graphite; graphene; and hydrophobic silica) using classical colloid chemistry approaches. Potentiometric titrations showed that these surfaces acquired less charge from proton-related reactions than oxide minerals. The data from batch-type titrations for PTFE powder did not show an effect of ionic strength, which was also in contrast with results for classical colloids. In agreement with classical colloids, the electrokinetic results for inert surfaces showed the typical salt level dependence. In some cases, the point of zero net proton charge as determined from mass and tentatively from acid–base titration differed from isoelectric points, which has also been previously observed, for example by Chibowski and co-workers for ice electrolyte interfaces. Finally, we found no evidence for surface contaminations of our PTFE particles before and after immersion in aqueous solutions. Only in the presence of NaCl-containing solutions did cryo-XPS detect oxygen from water. We believe that our low isoelectric points for PTFE were not due to impurities. Moreover, the measured buffering at pH 3 could not be explained by sub-micromolar concentrations of contaminants. The most comprehensive explanation for the various sets of data is that hydroxide ion accumulation occurred at the interfaces between inert surfaces and aqueous solutions.

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  • 340.
    Barker, Paul Michael
    et al.
    Laboratory for Nanoscale Materials Science, Empa, Dübendorf, Switzerland.
    Konstantinidis, Stephanos
    Chimie des Interactions Plasma-Surface (ChIPS), Université de Mons, Belgium.
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Britun, Nikolay
    Chimie des Interactions Plasma-Surface (ChIPS), Université de Mons, Belgium.
    Patscheider, Jörg
    Laboratory for Nanoscale Materials Science, Empa, Dübendorf, Switzerland.
    An investigation of c-HiPIMS discharges during titanium deposition2014In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 258, p. 631-638Article in journal (Refereed)
    Abstract [en]

    Abstract A modified version of high power impulse magnetron sputtering (HiPIMS) has been used to deposit titanium films at higher deposition rates than for conventional HiPIMS whilst maintaining similar pulse voltages and peak currents. This process, named chopped-HiPIMS (c-HiPIMS) utilises pulses decomposed into several short single pulses instead of single HiPIMS pulses. Experiments show that manipulating the pulse sequence during c-HiPIMS, i.e. the tÎŒon and tÎŒoff times (explained in the glossary) allows for an increase of the deposition rate; increases of up to 150% are reported here for selected conditions. Further, deposition rates higher than those measured using direct current magnetron sputtering are also shown. Investigations by optical emission and optical absorption spectroscopy at the substrate show that the increase of deposition rate is not a consequence of different ion concentrations arriving at the substrate when changing the micro-pulse-off times of c-HiPIMS. Thus alternative reasons for the enhanced deposition rate during c-HiPIMS deposition of metal films are discussed. It is demonstrated that film micro-structure maintains the void free, dense nature typically demonstrated by HiPIMS deposited coatings whilst at enhanced deposition rates. Thus c-HiPIMS allows for the preparation of dense films with the benefit of faster growth rates.

  • 341.
    Baryshnikov, Gleb V.
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Bohdan Khmelnytsky National University, Ukraine.
    Gawrys, Pawel
    Ivaniuk, Khrystyna
    Witulski, Bernhard
    Whitby, Richard J.
    Al-Muhammad, Ayham
    Minaev, Boris
    Cherpak, Vladyslav
    Stakhira, Pavlo
    Volyniuk, Dmytro
    Wiosna-Salyga, Gabriela
    Luszczynska, Beata
    Lazauskas, Algirdas
    Tamulevicius, Sigitas
    Grazulevicius, Juozas V.
    Nine-ring angular fused biscarbazoloanthracene displaying a solid state based excimer emission suitable for OLED application2016In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 4, no 24, p. 5795-5805Article in journal (Refereed)
    Abstract [en]

    A new biscarbazoloanthracene consisting of nine fused aromatic rings, including two pyrrole units, has been obtained in a straightforward and convergent synthesis. Computational chemistry and conformational analysis revealed that the semiconductor's molecule is not planar, the two carbazole moieties being helical twisted from the plane of the anthracene unit. Photophysical and electrochemical measurements showed that this angular fused heteroacene has a low lying HOMO energy level with a wide band gap despite its extended pi-conjugated molecular framework. Based on its relatively low-lying HOMO level, the semiconductor promises a high environmental stability in comparison to other related linear fused acenes and heteroacenes. The biscarbazoloanthracene has been applied as the light emitting layer in a white light emitting diode (WOLED). It is proposed that the white OLED feature is due to dual light emission properties from the active semiconductor layer being based on both the molecular luminescence of the small molecule and a discrete excimer emission made possible by suitable aggregates in the solid state. Noteworthy, this is the first reported example of such a behavior observed in a small molecule heteroacene rather than an oligomer or a polymer.

  • 342.
    Barzegar, Hamid Reza
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Gracia-Espino, Eduardo
    Umeå University, Faculty of Science and Technology, Department of Physics. Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sharifi, Tiva
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Nitze, Florian
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Nitrogen Doping Mechanism in Small Diameter Single-Walled Carbon Nanotubes: Impact on Electronic Properties and Growth Selectivity2013In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 117, no 48, p. 25805-25816Article in journal (Refereed)
    Abstract [en]

    Nitrogen doping in carbon nanostructures has attracted interest for more than a decade, and recent implementation of such structures in energy conversion systems has boosted the interest even more. Despite numerous studies, the structural conformation and stability of nitrogen functionalities in small diameter single-walled carbon nanotubes (SWNTs), and the impact of these functionalities on the electronic and mechanical properties of the SWNTs, are incomplete. Here we report a detailed study on nitrogen doping in SWNTs with diameters in the range of 0.8?1.0 nm, with well-defined chirality. We show that the introduction of nitrogen in the carbon framework significantly alters the stability of certain tubes, opening for the possibility to selectively grow nitrogen-doped SWNTs with certain chirality and diameter. At low nitrogen concentration, pyridinic functionalities are readily incorporated and the tubular structure is well pertained. At higher concentrations, pyrrolic functionalities are formed, which leads to significant structural deformation of the nanotubes and hence a stop in growth of crystalline SWNTs. Raman spectroscopy is an important tool to understand guest atom doping and electronic charge transfer in SWNTs. By correlating the influence of defined nitrogen functionalities on the electronic properties of SWNTs with different chirality, we make precise interpretation of experimental Raman data. We show that the previous interpretation of the double-resonance G?-peak in many aspects is wrong and instead can be well-correlated to the type of nitrogen doping of SWNTs originating from the p- or n-doping nature of the nitrogen incorporation. Our results are supported by experimental and theoretical data.

  • 343.
    Bashir, Amna
    et al.
    Nanyang Technol Univ, Energy Res Inst, ERI N, Res Techno Plaza,X Frontier Block,Level 5, Singapore 637553, Singapore;Nanyang Technol Univ, Sch Mat Sci & Engn, Nanyang Ave, Singapore 639798, Singapore.
    Lew, Jia Haur
    Nanyang Technol Univ, Energy Res Inst, ERI N, Res Techno Plaza,X Frontier Block,Level 5, Singapore 637553, Singapore.
    Shukla, Sudhanshu
    Nanyang Technol Univ, Energy Res Inst, ERI N, Res Techno Plaza,X Frontier Block,Level 5, Singapore 637553, Singapore.
    Gupta, Disha
    Nanyang Technol Univ, Sch Mat Sci & Engn, Nanyang Ave, Singapore 639798, Singapore.
    Baikie, Tom
    Nanyang Technol Univ, Energy Res Inst, ERI N, Res Techno Plaza,X Frontier Block,Level 5, Singapore 637553, Singapore.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Patidar, Rahul
    Nanyang Technol Univ, Energy Res Inst, ERI N, Res Techno Plaza,X Frontier Block,Level 5, Singapore 637553, Singapore;Indian Inst Sci Educ & Res, Pune 411008, Maharashtra, India.
    Bruno, Annalisa
    Nanyang Technol Univ, Energy Res Inst, ERI N, Res Techno Plaza,X Frontier Block,Level 5, Singapore 637553, Singapore.
    Mhaisalkar, Subodh
    Nanyang Technol Univ, Energy Res Inst, ERI N, Res Techno Plaza,X Frontier Block,Level 5, Singapore 637553, Singapore;Nanyang Technol Univ, Sch Mat Sci & Engn, Nanyang Ave, Singapore 639798, Singapore.
    Akhter, Zareen
    Quaid I Azam Univ, Dept Chem, Islamabad 45320, Pakistan.
    Cu-doped nickel oxide interface layer with nanoscale thickness for efficient and highly stable printable carbon-based perovskite solar cell2019In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 182, p. 225-236Article in journal (Refereed)
    Abstract [en]

    The power conversion efficiency (PCE) of hole conductor free carbon-based perovskite solar cells (PSCs) is restricted by the poor charge extraction and recombination losses at the carbon-perovskite interface. For the first time we successfully demonstrated incorporation of thin layer of copper doped nickel oxide (Cu:NiOx) nanoparticles in carbon-based PSCs, which helps in improving the performance of these solar devices. Cu:NiOx nanoparticles have been synthesized by a facile chemical method, and processed into a paste for screen printing. Extensive X-ray Absorption Spectroscopy (XAS) analysis elucidates the co-ordination of Cu in a NiOx matrix and indicates the presence of around 5.4% Cu in the sample. We fabricated a monolithic perovskite module on a 100 cm(2) glass substrate (active area of 70 cm(2)) with a thin Cu:NiOx layer (80 nm), where the champion device shows an appreciated power conversion efficiency of 12.1% under an AM 1.5G illumination. To the best of our knowledge, this is the highest reported efficiency for such a large area perovskite solar device. I-V scans show that the introduction of Cu:NiOx mesoporous scaffold increases the photocurrent, and yields fill factor (FF) values exceeding 57% due to the better interface and increased hole extraction efficiency. Electrochemical Impedance Spectroscopy (EIS) results reinforce the above results by showing the reduction in recombination resistance (R-rec) of the PSCs that incorporates Cu:NiOx interlayer. The perovskite solar modules with a Cu:NiOx layer are stable for more than 4500 h in an ambient environment (25 degrees C and 65% RH), with PCE degradation of less than 5% of the initial value.

  • 344.
    Bashir, Tariq
    et al.
    University of Borås, School of Engineering.
    Persson, Nils-Krister
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Smart Textiles: A novel concept of functionalizing textile materials2013Conference paper (Refereed)
    Abstract [en]

    Electrically conductive textile materials are the key components in smart and interactive textile applications. In our research, we introduced functionalities in commercially available textile substrates (fibers and fabrics) by coating them with conjugated polymer, such as poly (3,4-ethylenedioxythiophene) (PEDOT) [1-2]. In order to get conductivities that are of use, an efficient technique, chemical vapor deposition (CVD), was used. The obtained coated fibers and fabrics exhibited good electro-mechanical properties and can be utilized for a number of electronic applications, such as stretch sensors, anti-static air filters and electrodes for bio-fuel cells.

  • 345.
    Bashir, Tariq
    et al.
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Persson, Nils-Krister
    [external].
    Production of PEDOT Coated Conductive Fibers for Smart & Interactive Textile Applications2012Conference paper (Refereed)
  • 346.
    Bashir, Tariq
    et al.
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Ramamoorthy, Sunil Kumar
    Persson, Nils-Krister
    University of Borås, School of Engineering.
    All-organic conductive fibers for smart and interactive textile applications2013Conference paper (Other academic)
  • 347.
    Batalovic, K.
    et al.
    Univ Belgrade, Natl Inst Republ Serbia, VINCA Inst Nucl Sci, Belgrade, Serbia.;Ctr Excellence Hydrogen & Renewable Energy CONVIN, POB 522, Belgrade 11001, Serbia..
    Radakovic, J.
    Univ Belgrade, Natl Inst Republ Serbia, VINCA Inst Nucl Sci, Belgrade, Serbia.;Ctr Excellence Hydrogen & Renewable Energy CONVIN, POB 522, Belgrade 11001, Serbia..
    Bundaleski, N.
    Univ Belgrade, Natl Inst Republ Serbia, VINCA Inst Nucl Sci, Belgrade, Serbia.;Nova Univ Lisbon, Sch Sci & Technol, Ctr Phys & Technol Res, P-2829516 Caparica, Portugal..
    Rakocevic, Z.
    Univ Belgrade, Natl Inst Republ Serbia, VINCA Inst Nucl Sci, Belgrade, Serbia..
    Pasti, I
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia..
    Skorodumova, Natalia V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Rangel, C. M.
    Natl Lab Energy & Geol, LNEG, Paco do Lumiar 22, P-1649038 Lisbon, Portugal..
    Origin of photocatalytic activity enhancement in Pd/Pt-deposited anatase N-TiO2 – experimental insights and DFT study of the (001) surface2020In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 22, no 33, p. 18536-18547Article in journal (Refereed)
    Abstract [en]

    In pursuit of the ideal photocatalyst, cheap and stable semiconductor TiO(2)is considered to be a good choice if one is able to reduce its band gap and decrease the recombination rate of charge carriers. The approach that offers such improvements for energy conversion applications is the modification of TiO(2)with nitrogen and noble metals. However, the origin of these improvements and possibilities for further design of single-atom catalysts are not always straightforward. To shed light on the atomic-scale picture, we modeled the nitrogen-doped (001) anatase TiO(2)surface as a support for palladium and platinum single-atom deposition. The thermodynamics of various synthesis routes for Pd/Pt deposition and nitrogen doping is considered based on density functional theory (DFT)-calculated energies, highlighting the effect of nitrogen doping on metal dimer formation and metal-support interaction. XPS analysis of the valence band of the modified TiO(2)nanocrystals, and the calculated charge transfer and electronic structure of single-atom catalysts supported on the (001) anatase TiO(2)surface provide an insight into modifications occurring in the valence zone of TiO(2)due to nitrogen doping and Pd/Pt deposition at the surface. DFT results also show that substitutional nitrogen doping significantly increases metal-support interaction, while interstitial nitrogen doping promotes only Pt-support interaction.

  • 348.
    Bates, William P.
    et al.
    Department of Engineering Science, University West, Trollhättan (SWE).
    Patel, Vivek
    University West, Department of Engineering Science, Division of Welding Technology.
    Rana, Harikrishna
    Department of Engineering, University of Palermo, Palermo (ITA).
    Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    De Backer, Jeroen
    University West, Department of Engineering Science, Division of Production Systems. Friction Welding Process Section, TWI Ltd., Cambridge (GBR).
    Igestrand, Mattias
    University West, Department of Engineering Science, Division of Welding Technology.
    Fratini, Livan
    Department of Engineering, University of Palermo, Palermo (ITA).
    Properties Augmentation of Cast Hypereutectic Al-Si Alloy Through Friction Stir Processing2022In: Metals and Materials International, ISSN 1598-9623, E-ISSN 2005-4149Article in journal (Refereed)
    Abstract [en]

    The present endeavour is to augment mechanical attributes via friction stir processing (FSP) in hypereutectic aluminium-silicon castings by the means of microstructural modifications and defects reduction. Wherein, the study proceeds with mainly two approaches namely, alteration in tool revolution (TR) and the number of FSP passes. The prepared specimens were evaluated investigating volume fraction of porosities, microstructural characterizations and microhardness. Therefrom, the specimen with highest number of passes delivered most uniform properties resulting from the reduction in casting porosities and refined silicon particle uniform distribution throughout friction stir processed zone. This endeavour may be considered as a footstep towards more industrial readied material transformation.

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    Springer
  • 349. Bathen, M. E.
    et al.
    Linnarsson, Margareta K.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Ghezellou, M.
    Hassan, J. U.
    Vines, L.
    Influence of carbon cap on self-diffusion in silicon carbide2020In: Crystals, ISSN 2073-4352, Vol. 10, no 9, p. 1-11, article id 752Article in journal (Refereed)
    Abstract [en]

    Self-diffusion of carbon (12C and13C) and silicon (28Si and30Si) in 4H silicon carbide has been investigated by utilizing a structure containing an isotope purified 4H-28Si12C epitaxial layer grown on an n-type (0001) 4H-SiC substrate, and finally covered by a carbon capping layer (C-cap). The13C and30Si isotope profiles were monitored using secondary ion mass spectrometry (SIMS) following successive heat treatments performed at 2300–2450◦C in Ar atmosphere using an inductively heated furnace. The30Si profiles show little redistribution within the studied temperature range, with the extracted diffusion lengths for Si being within the error bar for surface roughening during annealing, as determined by profilometer measurements. On the other hand, a significant diffusion of13C was observed into the isotope purified layer from both the substrate and the C-cap. A diffusivity of D = 8.3 × 106 e−10.4/kBT cm2/s for13C was extracted, in contrast to previous findings that yielded lower both pre-factors and activation energies for C self-diffusion in SiC. The discrepancy between the present measurements and previous theoretical and experimental works is ascribed to the presence of the C-cap, which is responsible for continuous injection of C interstitials during annealing, and thereby suppressing the vacancy mediated diffusion.

  • 350.
    Batili, Hazal
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Synthesis, Electrophoretic Deposition, and Characterization of Nanostructured Thermoelectric Materials2023Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The world’s increasing demand for energy and supplying this energy dominantlyfrom fossil fuels has a major impact on global climate change. Theenergy crisis has gotten more alarming in the recent years which increasedthe motivation for replacing fossil fuels with greener routes for energy harvest.There are various technologies developed for harvesting energy, andthe ability to recover energy from waste heat at a wide range of temperatures (from room temperature to more than 1000C) distinguished thethermoelectric (TE) materials from the rest. The drawback about the thermoelectricdevices is that they are too inefficient to be cost-effective in manyapplications, and the developments in nanotechnology is providing somesolutions to increase the efficiency of these materials and devices.

    The field of thermoelectrics suffer from large discrepancy of theresults in the literature, which is generally attributed to the variations inthe materials qualities, urging a need for the development of synthetictechniques that can lead to large-scale TE materials in reasonable timeframe. In this thesis, three different routes for rapid, scalable, and energyefficient, wet-chemical synthetic techniques for bismuth chalcogenidecompounds are presented. Microwave assisted heating during reactionprovided better control over the particle properties while reducing thereaction time and carbon footprint of the synthetic method, leading tomaterials bismuth chalcogenides with promising TE transport propertiesin a scalable and reproducible manner.

    Hybrid TE materials, and recently emerging solid-liquid TE materialsconcept, requires fabrication of porous TE films, to study the effect of variousinterfaces, including solid and liquid electrolytes. For this purpose, wedeveloped and optimized the electrophoretic deposition (EPD) process toprepare nanostructured porous TE films by preserving the size and morphologyof the as-synthesized bismuth chalcogenide particles. A new glass based substrate is designed and fabricated to study the electronic transportproperties of the electrically active films prepared via EPD. Using this platform,we could clearly demonstrate the significance of the synthetic methodon the surface chemistry and resultant transport properties of the TE materials.The methods and materials developed in this thesis are expected toimpact and expedite further developments in the field of thermoelectrics.

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    Summary
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