Endre søk
Begrens søket
272829303132 1451 - 1500 of 1563
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1451.
    Yang, Junyu
    et al.
    Jinan Univ, Peoples R China.
    Lin, Yuanbao
    Jinan Univ, Peoples R China.
    Zheng, Wenhao
    Jinan Univ, Peoples R China.
    Liu, Alei
    Jinan Univ, Peoples R China.
    Cai, Wanzhu
    Jinan Univ, Peoples R China.
    Yu, Xiaomin
    Jinan Univ, Peoples R China.
    Zhang, Fengling
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten. Jinan Univ, Peoples R China.
    Liang, Quanbin
    South China Univ Technol, Peoples R China.
    Wu, Hongbin
    South China Univ Technol, Peoples R China.
    Qin, Donghuan
    South China Univ Technol, Peoples R China.
    Hou, Lintao
    Jinan Univ, Peoples R China.
    Roll-to-Roll Slot-Die-Printed Polymer Solar Cells by Self-Assembly2018Inngår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, nr 26, s. 22485-22494Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Extremely simplified one-step roll-to-roll slot-die-printed flexible indium tin oxide (ITO)-free polymer solar cells (PSCs) are demonstrated based on the ternary blends of electron-donor polymer thieno[3,4-b]thiophene/benzodithiophene, electron-acceptor fullerene [6,6]-phenyl-C-71-butyric acid methyl ester, and electron-extracting polymer poly[(9,9-bis(3-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFN) at room temperature (RT) in ambient air. The flexible ITO-free PSC exhibits a comparable power conversion efficiency (PCE) with the device employing complicated two-step slot-die printing (5.29% vs 5.41%), which indicates that PFN molecules can migrate from the ternary nanocomposite toward the Ag cathode via vertical self-assembly during the one-step slot-die printing process in air. To confirm the migration of PFN, the morphology and elemental analysis as well as charge transport of different active layers are investigated by the in situ transient film drying process, transmission electron microscopy, atomic force microscopy, contact angle and surface energy, X-ray photoelectron spectroscopy, scanning electron microscopy, impedance spectroscopy, transient photovoltage and transient photocurrent, and laser-beam-induced current. Moreover, the good air and mechanical stability of the flexible device with a decent PCE achieved in 1 cm(2) PSCs at RT in air suggests the feasibility of energy-saving and time-saving one-step slot-die printing to large-scale roll-to-roll manufacture in the future.

  • 1452.
    Yang, Lei
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. Xian Univ Architecture & Technol, Sch Environm & Municipal Engn, Xian 710055, Shaanxi, Peoples R China.
    Schölin, Rebecka
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Gabrielsson, Erik
    Royal Inst Technol, Sch Chem Sci & Engn, Organ Chem, S-11428 Stockholm, Sweden.
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Rensmo, Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Sun, Licheng
    Xian Univ Architecture & Technol, Sch Environm & Municipal Engn, Xian 710055, Shaanxi, Peoples R China.
    Hagfeldt, Anders
    Swiss Fed Inst Technol, Dept Chem & Chem Engn, Lab Photomol Sci, Stn 6, CH-1015 Lausanne, Switzerland.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Johansson, Erik M. J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Experimental and Theoretical Investigation of the Function of 4-tert-Butyl Pyridine for Interface Energy Level Adjustment in Efficient Solid-State Dye-Sensitized Solar Cells2018Inngår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, nr 14, s. 11572-11579Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    4-tert-Butylpyridine (t-BP) is commonly used in solid state dye-sensitized solar cells (ssDSSCs) to increase the photovoltaic performance. In this report, the mechanism how t-BP functions as a favorable additive is investigated comprehensively. ssDSSCs were prepared with different concentrations of t-BP, and a clear increase in efficiency was observed up to a maximum concentration and for higher concentrations the efficiency thereafter decreases. The energy level alignment in the complete devices was measured using hard X-ray photoelectron spectroscopy (HAXPES). The results show that the energy levels of titanium dioxide are shifted further away from the energy levels of spiro-OMeTAD as the t-BP concentration is increased. This explains the higher photovoltage obtained in the devices with higher t-BP concentration. In addition, the electron lifetime was measured for the devices and the electron lifetime was increased when adding t-BP, which can be explained by the recombination blocking effect at the surface of TiO2. The results from the HAXPES measurements agree with those obtained from density functional theory calculations and give an understanding of the mechanism for the improvement, which is an important step for the future development of solar cells including t-BP.

  • 1453.
    Yang, Rong
    et al.
    Nanjing Technical University, Peoples R China.
    Zhang, Li
    Nanjing Technical University, Peoples R China.
    Cao, Yu
    Nanjing Technical University, Peoples R China.
    Miao, Yanfeng
    Nanjing Technical University, Peoples R China.
    Ke, You
    Nanjing Technical University, Peoples R China.
    Wei, Yingqiang
    Nanjing Technical University, Peoples R China.
    Guo, Qiang
    Nanjing Technical University, Peoples R China.
    Wang, Ying
    Nanjing Technical University, Peoples R China.
    Rong, Zhaohua
    Nanjing Technical University, Peoples R China.
    Wang, Nana
    Nanjing Technical University, Peoples R China.
    Li, Renzhi
    Nanjing Technical University, Peoples R China.
    Wang, Jianpu
    Nanjing Technical University, Peoples R China.
    Huang, Wei
    Nanjing Technical University, Peoples R China; Nanjing University of Posts and Telecommun, Peoples R China; Nanjing University of Posts and Telecommun, Peoples R China.
    Gao, Feng
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Inhomogeneous degradation in metal halide perovskites2017Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 111, nr 7, artikkel-id 073302Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Although the rapid development of organic-inorganic metal halide perovskite solar cells has led to certified power conversion efficiencies of above 20%, their poor stability remains a major challenge, preventing their practical commercialization. In this paper, we investigate the intrinsic origin of the poor stability in perovskite solar cells by using a confocal fluorescence microscope. We find that the degradation of perovskite films starts from grain boundaries and gradually extend to the center of the grains. Firmly based on our findings, we further demonstrate that the device stability can be significantly enhanced by increasing the grain size of perovskite crystals. Our results have important implications to further enhance the stability of optoelectronic devices based on metal halide perovskites. Published by AIP Publishing.

  • 1454.
    Yang, Xia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Polymerkemi.
    Multi-functional Hyaluronan Based Biomaterials for Biomedical Applications2014Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis presents strategies for constructing multi-functional biomaterials based on hyaluronan (HA) derivatives for various biomedical applications, such as drug delivery, tissue regeneration, and imaging biomaterials. The aim of this study is to improve the functionalities of HA biomaterials as well as simplify the preparation procedures.  Native HA polymer contains D-glucuronic acid residue with a carboxyl group per disaccharide unit that can be easily modified by carbodiimide-mediated amidation reaction. Therefore, we have designed a series of orthogonal groups (hydrazide, carbazate, aldehyde, and thiol) that can be linked to HA under mild conditions using the carbodiimide chemistry. Multiple functionalities can be introduced to the obtained HA derivatives via chemoselective “click”-type transformations.  

    The modified HA derivatives were used for the preparation of either nanogel particles (NPs) or bulk hydrogels. Due to “click” character of the reactions used, structural HA transformations were performed with high fidelity on different scales including molecular (polymers), nanometer (NPs), and a visible scale (bulk hydrogels). By linking pyrene or camptothecin to hydrophilic HA backbone, amphiphilic polymers were obtained and utilized as drug delivery carriers or prodrugs, respectively. Subsequently, physically loaded drug (doxorubicin) could be released upon degradation of HA carriers, while the chemically linked camptothecin was released intact by a thiol-triggered cleavage reaction. Bisphosphonated HA (HA-BP) polymers were prepared to induce hydrogel scaffold bio-mineralization for bone regeneration application. Moreover, we could recruit strong binding capacity of bisphosphonate (BP) groups to calcium ions for the formation of physically crosslinked HA-BP gel upon simple mixing of the polymer and calcium phosphate nanoparticle components. This gel was more stable in vivo compared to hydrazone crosslinked HA gels. Furthermore, the hydrogel composed of fluorine-19 (19F) linked HA polymer was successfully observed by both 1H and 19F MR imaging.        

    In conclusion, the presented herein study describes new approaches for building up multi-functional biomaterials from the HA-based blocks. The utilization of carbodiimide and click chemistries along with the enzymatic degradation of HA allowed simple and efficient interconversion between HA macromolecules, nanoparticles and macroscopic hydrogels. These HA-based biomaterials show high potential for use in the fields of drug delivery, bone regeneration, and imaging techniques.

  • 1455.
    Yang, Xia
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Polymerkemi.
    Yi, Sun
    Radboud University Nijmegen Medical Centre.
    Kootala, Sujit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Polymerkemi.
    Hilborn, Jöns
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Polymerkemi.
    Heerschap, Arend
    Radboud University Nijmegen Medical Centre.
    Ossipov, Dmitri
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Polymerkemi.
    Injectable hyaluronic acid hydrogel for F-19 magnetic resonance imaging2014Inngår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 110, s. 95-99Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report on a19F labeled injectable hyaluronic acid (HA) hydrogel that can be monitored by both 1H and 19F MR imaging. The HA based hydrogel formed via carbazone reaction can be obtained within a minute by simple mixing of HA-carbazate and HA-aldehyde derivatized polymers. 19F contrast agent was linked to with carbazate and thiol dually functionalized HA via orthogonal Michael addition reaction which afforded cross-linkable and 19F labeled HA. The 19F labeling of HA polymer did not affect the mechanical properties of the formed hydrogel. As a result, the shape of a hydrogel sample could be imaged very well by both 1H MRI and high resolution19F MRI. This hydrogel has high potential in clinical applications since it is injectable, biocompatible, and can be tracked in a minimally invasive manner. The present approach can be applied in preparation of injectable 19F labeled hydrogel biomaterials from other natural biomacromolecules.

  • 1456.
    Yang, Xiao
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori. Yanshan Univ, Coll Civil Engn & Mech, Qin Huangdao 066004, Hebei, Peoples R China..
    Li, Huijian
    Yanshan Univ, Coll Civil Engn & Mech, Qin Huangdao 066004, Hebei, Peoples R China..
    Ahuja, Rajeev
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori. Royal Inst Technol KTH, Dept Mat & Engn, S-10044 Stockholm, Sweden..
    Kang, Taewon
    Dongguk Univ, Nano Informat Technol Acad, Seoul 100715, South Korea..
    Luo, Wei
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori. Dongguk Univ, Nano Informat Technol Acad, Seoul 100715, South Korea..
    Formation and electronic properties of palladium hydrides and palladium-rhodium dihydride alloys under pressure2017Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, artikkel-id 3520Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present the formation possibility for Pd-hydrides and Pd-Rh hydrides system by density functional theory (DFT) in high pressure upto 50 GPa. Calculation confirmed that PdH2 in face-centered cubic (fcc) structure is not stable under compression that will decomposition to fcc-PdH and H-2. But it can be formed under high pressure while the palladium is involved in the reaction. We also indicate a probably reason why PdH2 can not be synthesised in experiment due to PdH is most favourite to be formed in Pd and H-2 environment from ambient to higher pressure. With Rh doped, the Pd-Rh dihydrides are stabilized in fcc structure for 25% and 75% doping and in tetragonal structure for 50% doping, and can be formed from Pd, Rh and H-2 at high pressure. The electronic structural study on fcc type PdxRh1-xH2 indicates the electronic and structural transition from metallic to semi-metallic as Pd increased from x = 0 to 1.

  • 1457.
    Yang, Xichuan
    et al.
    Dalian Univ Technol, State Key Lab Fine Chem, Linggong Rd 2, Dalian 116024, Liaoning, Peoples R China..
    Wang, Weihan
    Dalian Univ Technol, State Key Lab Fine Chem, Linggong Rd 2, Dalian 116024, Liaoning, Peoples R China..
    Zhang, Yanyun
    Dalian Univ Technol, State Key Lab Fine Chem, Linggong Rd 2, Dalian 116024, Liaoning, Peoples R China..
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Improving the power conversion efficiency of solid state dye sensitized solar cells with a N-oxoammonium salt: 2,2,6,6-Tetramethyl-1-oxopiperidinebromide2018Inngår i: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 170, s. 1001-1008Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    P-type doping is a rational strategy for the enhancement of hole transporting properties of the organic semiconductors as well as the device performance of organic photo-electric devices. We originally introduce a stable and solution processed p-type dopant based on N-oxoammonium salts termed 2,2,6,6-tetramethyl-1-oxopiperidinebromide salt (TEMPO-Br) for 2,2',7,7'-tetrakis(N, N-di-p-methoxyphenyl-amine)9,9'-spirobifluorene (Spiro-OMeTAD) based solid state dye sensitized solar cells (ssDSC). By introducing TEMPO-Br doped Spiro-OMeTAD and a commercialized D-pi-A sensitizer into ssDSCs, a promising device performance of 6.83% is achieved under simulated AM 1.5G solar irradiation (100 mW cm(-2)), which is significantly better than the control devices ( similar to 1.7 times). The doping effect of TEMPO-Br on the photophysical and electrochemical properties of Spiro-OMeTAD, solid state device performance, cationic dye regeneration kinetics and preliminary long-term stability have been systematically investigated. This work indicates a potential application of N-oxoammonium salts as chemical P-type dopants for triphenylamine based hole transporting materials in solid state photo-electric devices.

  • 1458.
    Yao, Kun
    et al.
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Huang, Shu
    KTH, Skolan för bioteknologi (BIO).
    Tang, Hu
    KTH, Skolan för bioteknologi (BIO).
    Xu, Y.
    Buntkowsky, G.
    Berglund, Lars A.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Zhou, Qi
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Bioinspired Interface Engineering for Moisture Resistance in Nacre-Mimetic Cellulose Nanofibrils/Clay Nanocomposites2017Inngår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, nr 23, s. 20169-20178Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The interfacial adhesion design between "mortar" and "bricks" is essential for mechanical and barrier performance of nanocellulose-based nacre-mimetic nanocomposites, especially at high moisture conditions. To address this fundamental challenge, dopamine (DA) has been conjugated to cellulose nanofibrils (CNFs) and subsequently assembled with montmorillonite (MTM) to generate layered nanocomposite films inspired by the strong adhesion of mussel adhesive proteins to inorganic surfaces under water. The selective formation of catechol/metal ion chelation and hydrogen bonding at the interface between MTM platelets and CNFs bearing DA renders transparent films with strong mechanical properties, particularly at high humidity and in wet state. Increasing the amount of conjugated DA on CNFs results in nanocomposites with increased tensile strength and modulus, up to 57.4 MPa and 1.1 GPa, respectively, after the films are swollen in water. The nanocomposites also show excellent gas barrier properties at high relative humidity (95%), complementing the multifunctional property profile.

  • 1459. Yao, Mingguang
    et al.
    Fan, Xianhong
    Liu, Dedi
    Liu, Bingbing
    Wågberg, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Synthesis of differently shaped C(70) nano/microcrystals by using various aromatic solvents and their crystallinity-dependent photoluminescence2012Inngår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 50, nr 1, s. 209-215Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report a simple synthesis of Cm microcrystals by a fast solvent-assisted evaporation method by selectively using aromatic solvents with halogen radicals as a controller. In a detailed analysis we show that depending on solvent, C(70) concentration in the solution, and synthesis temperature both C(70) microrods and microcubes can be produced. The samples were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. From meta-type solvents microrods or microcrystal cubes grow with a single orthorhombic or a monoclinic structure or a mixture of both. These crystals show traces of solvents in the structure. From para-type solvents cubic (or rectangular) crystals grow with a hexagonal structure and with no trace of solvents. Room temperature photoluminescence (PL) of the C(70) crystal samples reveals that the PL efficiency of the crystals increases with crystalline order and that the best crystalline Cm cube crystals show 10 times higher PL efficiency than that of pristine C(70) polycrystalline samples. (C) 2011 Elsevier Ltd. All rights reserved.

  • 1460. Yao, Qingxia
    et al.
    Su, Jie
    Zou, Xiaodong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    SUMOF-5: a mesoporous metal-organic framework with the tbo topology built from the dicopper paddle-wheel cluster and a new tritopic linker2013Inngår i: Zeitschrift fur Kristallographie, ISSN 0044-2968, Vol. 228, nr 7, s. 323-329Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A mesoporous metal-organic framework Cu-3(PTB)(2)(H2O)(3) center dot guest (denoted as SUMOF-5) has been synthesized using a new tritopic linker pyridine-2,4,6-tribenzoic acid (H3PTB). SUMOF-5 is cubic with the space group Fm (3) over barm and a = 47.272(3) angstrom. The framework is built of the dicopper paddle-wheel secondary building unit (SBU) [Cu-2(OOC)(4)(H2O)(2)] and contains two different cavities of 1.22 and 2.33 nm in diameter, respectively. The framework topology follows the (3,4)-connected tbo net, and can be regarded as an extended version of Cu-3(BTC)(2)(H2O)(3) center dot guest (HKUST-1, BTC = benzene tricarboxylate). The structure of SUMOF-5 is compared to other MOFs built from dicopper paddle-wheels and tritopic linkers. SUMOF-5 has permanent porosity with a Langmuir surface area of 1733 m(2)/g and is stable in various organic solvents, which makes this material potentially useful as a crystalline carrier for loading molecular catalysts or drugs.

  • 1461. Yar, Mazher Ahmed
    et al.
    Wahlberg, Sverker
    Abuelnaga, Mohammad Omar
    Johnsson, Mats
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Muhammed, Mamoun
    Processing and sintering of yttrium-doped tungsten oxide nanopowders to tungsten-based composites2014Inngår i: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 49, nr 16, s. 5703-5713Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Innovative chemical methods are capable of fabricating nanoscale tungsten oxide compounds doped with various rare-earth elements with high purity and homogeneity, which can be processed under hydrogen into nanostructured oxide-dispersed tungsten composite powders having several potential applications. However, hydrogen reduction of doped tungsten oxide compounds is rather complex, affecting the morphology and composition of the final powder. In this study, we have investigated the reduction of tungstic acid in the presence of Y and we provide the experimental evidence that Y2O3 can be separated from Y-doped tungstic acid via hydrogen reduction to produce Y2O3-W powders. The processed powders were further consolidated by spark plasma sintering at different temperatures and holding times at 75 MPa pressure and characterized. The optimized SPS conditions suggest sintering at 1400 A degrees C for 3 min holding time to achieve higher density composites with an optimum finer grain size (3 A mu m) and a hardness value up to 420 H (V). Major grain growth takes place at temperatures above 1300 A degrees C during sintering. From the density values obtained, it is recommend to apply higher pressure before 900 A degrees C to obtain maximum density. Oxides inclusions present in the matrix were identified as Y2O3 center dot 3WO(3) and Y2O3 center dot WO3 during high resolution microscopic investigations.

  • 1462.
    Yasin, M. Naveed
    et al.
    Univ Auckland, New Zealand; Univ Auckland, New Zealand; Fac Engn, Canada.
    Brooke, Robert
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska fakulteten. Univ South Australia, Australia.
    Rudd, Sam
    Univ South Australia, Australia.
    Chan, Andrew
    Univ Auckland, New Zealand.
    Chen, Wan-Ting
    Univ Auckland, New Zealand.
    Waterhouse, Geoffrey I. N.
    Univ Auckland, New Zealand; Univ Auckland, New Zealand.
    Evans, Drew
    Univ South Australia, Australia.
    Rupenthal, Ilva D.
    Univ Auckland, New Zealand.
    Svirskis, Darren
    Univ Auckland, New Zealand.
    3-Dimensionally ordered macroporous PEDOT ion-exchange resins prepared by vapor phase polymerization for triggered drug delivery: Fabrication and characterization2018Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 269, s. 560-570Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper reports a simple fabrication strategy towards 3-dimensionally ordered macroporous (3DOM) poly(3,4-ethylenedioxythiophene) (PEDOT) thin films via vapor phase polymerization (VPP) coupled with colloidal crystal templating. PEDOT was synthesized by VPP over a colloidal crystal thin film composed of monodisperse polystyrene colloids functionalized with a Fe(III) tosylate catalyst, after which the polystyrene template was selectively removed. The resulting 3DOM PEDOT films comprised a face-centered cubic array of 280-290 nm spherical macropores in a PEDOT matrix, around 5-6 mu m thick. Cyclic voltammetry (CV) was used to probe electrochemistry and highlighted the merits of the fabrication strategy introduced here; the 3DOM PEDOT films exhibit a 2.9-fold increase in electrochemically available surface area compared to the non-templated PEDOT films. As a demonstration of functionality, ion-exchange of the dopant tosylate for the anionic drug dexamethasone phosphate (dexP(-)) was explored. Loading by passive ion exchange was three-fold higher for 3DOM PEDOT compared with non-templated PEDOT. Notably, CV-driven ion exchange was more efficient to load drug into the polymer than passive ion exchange, and occurred to similar extents for both non-templated PEDOT and 3DOM PEDOT structures. Following loading, minimal dexP(-) release was observed in the absence of an electrical stimulus, while dexP(-) release was triggered upon application of a suitable electrical stimulus. 3DOM PEDOT prepared by VPP thus represents a promising material for use as an ion exchange resin with drug loading achieved subsequent to polymerization and electrically triggered drug release demonstrated. (c) 2018 Elsevier Ltd. All rights reserved.

  • 1463.
    Ye, Fei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Synthesis of nanostructured and hierarchical materials for bio-applications2011Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    In recent years, nanostructured materials incorporated with inorganic particles and polymers have attracted attention for simultaneous multifunctional biomedical applications. This thesis summarized three works, which are preparation of mesoporous silica coated superparamagnetic iron oxide (Fe3O4@mSiO2) nanoparticles (NPs) as magnetic resonance imaging T2 contrast agents, polymer grafted Fe3O4@mSiO2 NPs response to temperature change, synthesis and biocompatibility evaluation of high aspect ratio (AR) gold nanorods.

    Monodisperse Fe3O4@mSiO2 NPs have been prepared through a sol-gel process. The coating thickness and particle sizes can be precisely controlled by varying the synthesis parameters. Impact of surface coatings on magnetometric and relaxometric properties of Fe3O4 NPs is studied. The efficiency of these contrast agents, evaluated by MR relaxivities ratio (r2/r1), is much higher than that of the commercial ones. This coating-thickness dependent relaxation behavior is explained due to the effects of mSiO2 coatings on water exclusion.

    Multifunctional core-shell composite NPs have been developed by growing thermo-sensitive poly(N-isopropylacrylamide-co-acrylamide) (P(NIPAAm-co-AAm)) on Fe3O4@mSiO2 NPs through free radical polymerization. Their phase transition behavior is studied, and their lower critical solution temperature (LCST) can be subtly tuned from ca. 34 to ca. 42 °C, suitable for further in vivo applications.

    A seedless surfactant-mediated protocol has been applied for synthesis of high AR gold nanorods with the additive of HNO3. A growth mechanism based on the effect of nitrate ions on surfactant micelle elongation and Ostwald ripening process is proposed. The biocompatibility of high AR nanorods was evaluated on primary human monocyte derived dendritic cells (MDDCs). Their minor effects on viability and immune regulatory markers support further development for medical applications.

  • 1464.
    Ye, Fei
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Qin, Jian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Multifunctional core-shell nanoparticles: superparamagnetic, mesoporous, and thermosensitive2011Inngår i: Journal of nanoparticle research, ISSN 1388-0764, E-ISSN 1572-896X, Vol. 13, nr 11, s. 6157-6167Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Multifunctional core-shell composite nanoparticles (NPs) have been developed by the combination of three functionalities into one entity, which is composed of a single Fe3O4 NP as the magnetic core, mesoporous silica (mSiO2) with cavities as the sandwiched layer, and thermosensitive poly(N-isopropylacrylamide-co-acrylamide) (P(NIPAAm-co-AAm)) copolymer as the outer shell. The mSiO2-coated Fe3O4 NPs (Fe3O4@mSiO2) are monodisperse and the particle sizes were varied from 25 to 95 nm by precisely controlling the thickness of mSiO2-coating layer. The P(NIPAAm-co-AAm) were then grown onto surface-initiator-modified Fe3O4@mSiO2 NPs through free radical polymerization. These core-shell composite NPs (designated as Fe3O4@mSiO2@P(NIPAAm-co-AAm)) were found to be superparamagnetic with high r2 relaxivity. To manipulate the phase transition behavior of these thermosensitive polymer-coated NPs for future in vivo applications, the characteristic lower critical solution temperature (LCST) was subtly tuned by adjusting the composition of the monomers to be around the human body temperature (i.e. 37 °C), from ca. 34 to ca. 42 °C. The thermal response of the core-shell composite NPs to the external magnetic field was also demonstrated. Owing to their multiple functionality characteristics, these porous superparamagnetic and thermosensitive NPs may prove valuable for simultaneous magnetic resonance imaging (MRI), temperature-controlled drug release, and temperature-programed magnetic targeting and separation applications.

  • 1465.
    Ye, Fei
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Vallhov, Helen
    Clinical Allergy Research Unit, Department of Medicine, Karolinska Institute and University Hospital Solna, Sweden.
    Qin, Jian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Daskalaki, Evangelia
    Clinical Allergy Research Unit, Department of Medicine, Karolinska Institutet and Universty Hospital Solan, Sweden.
    abhilash, Sugunan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Fornara, Andrea
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Gabrielsson, Susanne
    Clinical Allergy Research Unit, Department of Medicine, Karolinska Institutet and Universty Hospital Solan, Sweden.
    Scheynius, Annika
    Clinical Allergy Research Unit, Department of Medicine, Karolinska Institutet and Universty Hospital Solan, Sweden.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Synthesis of high aspect ratio gold nanorods and their effects on human antigen presenting dendritic cells2011Inngår i: International Journal Of Nanotechnology, ISSN 1475-7435, Vol. 8, nr 8-9, s. 631-652Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    High aspect ratio (AR) gold nanorods (NRs) attract great interest for biomedical applications due to their novel physicochemical properties. Here, we report a facile method for preparation of high AR gold NRs through a seedless surfactant-mediated protocol with the additive of nitric acid. High-resolution transmission electron microscopy studies showed that the concentration of nitric acid has great effects on the crystal structures of the initially formed nuclei and consequently the growth of gold NRs. A mechanism based on the effect of nitrate ions on surfactant micelle elongation and Ostwald ripening process is proposed for the growth of high AR gold NRs. The biocompatibility of high AR NRs was evaluated on primary human monocyte derived dendritic cells (MDDCs), and compared with that of spherical gold nanoparticles (NPs) and low AR NRs. Low AR (similar to 4.5) gold NRs induced considerable cell death due to CTAB, while spherical gold NPs (7 nm) and high AR (similar to 21) gold NRs showed no or minor effects on viability and immune regulatory markers, which supports the further development of high AR gold NRs for medical applications.

  • 1466.
    Yeşilbaş, Merve
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Boily, Jean-Francois
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Particle Size Controls on Water Adsorption and Condensation Regimes at Mineral Surfaces2016Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, artikkel-id 32136Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Atmospheric water vapour interacting with hydrophilic mineral surfaces can produce water films of various thicknesses and structures. In this work we show that mineral particle size controls water loadings achieved by water vapour deposition on 21 contrasting mineral samples exposed to atmospheres of up to ~16 Torr water (70% relative humidity at 25 °C). Submicrometer-sized particles hosted up to ~5 monolayers of water, while micrometer-sized particles up to several thousand monolayers. All films exhibited vibrational spectroscopic signals akin to liquid water, yet with a disrupted network of hydrogen bonds. Water adsorption isotherms were predicted using models (1- or 2- term Freundlich and Do-Do models) describing an adsorption and a condensation regime, respectively pertaining to the binding of water onto mineral surfaces and water film growth by water-water interactions. The Hygroscopic Growth Theory could also account for the particle size dependence on condensable water loadings under the premise that larger particles have a greater propensity of exhibiting of surface regions and interparticle spacings facilitating water condensation reactions. Our work should impact our ability to predict water film formation at mineral surfaces of contrasting particle sizes, and should thus contribute to our understanding of water adsorption and condensation reactions occuring in nature.

  • 1467.
    Yim, C. M.
    et al.
    UCL, Dept Chem, 20 Gordon St, London WC1H 0AJ, England; UCL, London Ctr Nanotechnol, 20 Gordon St, London WC1H 0AJ, England.
    Watkins, M. B,
    Lincoln Univ, Sch Math & Phys, Lincoln LN6 7TS, England.
    Wolf, Matthew
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi. UCL, Dept Phys & Astron, Gower St, London WC1E 6BT, England; UCL, London Ctr Nanotechnol, Gower St, London WC1E 6BT, England.
    Hermansson, Kersti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Thornton, G.
    UCL, Dept Chem, 20 Gordon St, London WC1H 0AJ, England; UCL, London Ctr Nanotechnol, 20 Gordon St, London WC1H 0AJ, England.
    Engineering Polarons at a Metal Oxide Surface2016Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 117, nr 11, artikkel-id 116402Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Polarons in metal oxides are important in processes such as catalysis, high temperature superconductivity, and dielectric breakdown in nanoscale electronics. Here, we study the behavior of electron small polarons associated with oxygen vacancies at rutile TiO2(110), using a combination of low temperature scanning tunneling microscopy (STM), density functional theory, and classical molecular dynamics calculations. We find that the electrons are symmetrically distributed around isolated vacancies at 78 K, but as the temperature is reduced, their distributions become increasingly asymmetric, confirming their polaronic nature. By manipulating isolated vacancies with the STM tip, we show that particular configurations of polarons are preferred for given locations of the vacancies, which we ascribe to small residual electric fields in the surface. We also form a series of vacancy complexes and manipulate the Ti ions surrounding them, both of which change the associated electronic distributions. Thus, we demonstrate that the configurations of polarons can be engineered, paving the way for the construction of conductive pathways relevant to resistive switching devices.

  • 1468. Yim, C.M.
    et al.
    Watkins, M.B.
    Pang, C.L.
    Wolf, Matthew J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Hermansson, Kersti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Thornton, G,
    Engeneering Polarons at a Metal Oxide Syrface2016Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114Artikkel i tidsskrift (Fagfellevurdert)
  • 1469. You, Qiangwei
    et al.
    Liu, Yongsheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Polytechnical University, Xi’an, Shanxi, PR China.
    Wan, Jiajia
    Shen, Zhijian
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Li, Hongxia
    Yuan, Bo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Sinosteel Luoyang Institute of Refractories Research Co., Ltd, PR China.
    Cheng, Laifei
    Wang, Gang
    Microstructure and properties of porous SiC ceramics by LPCVI technique regulation2017Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 43, nr 15, s. 11855-11863Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new gradient pore structure in porous SiC ceramics was fabricated by low pressure chemical vapor infiltration (LPCVI). Effects of deposition duration on the mechanical properties and permeability of porous SiC ceramics were investigated. Results demonstrated that pore diameter and shapes decreased from the surface to the interior along with LPCVI duration. Porous SiC ceramics with deposition duration of 160 h exhibited flexural strength of 48.05 MPa and fracture toughness of 1.30 MPa m(1/2), where 221% and 189% improvements were obtained compared to porous SiC ceramics without LPCVI, due to CVI-SiC layer strengthening effect. Additionally, at the same gas velocity, pressure drop increase rate was faster due to apparent porosity and pore size change.

  • 1470.
    You, Shujie
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Luzan, Serhiy
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Szabo, Tamas
    Talyzin, Alexandr
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Effect of synthesis method on solvation and exfoliation of graphite oxide2013Inngår i: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 52, s. 171-180Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Graphite oxides (GOs) synthesized by Brodie’s and Hummers’ methods are significantly different with respect to hydration, solvation and exfoliation properties. Hummers GO is more easily intercalated by liquid water and alcohols, exhibiting osmotic type of swelling. In contrast, Brodie GO shows crystalline swelling in alcohol solvents with step-like insertion of methanol or ethanol monolayers. However, the stronger hydration and easier dispersion in water observed for Hummers GO do not correlate with better dispersion of graphene powder obtained by thermal exfoliation. Higher surface area graphene powder was obtained by exfoliation of Brodie GO, while the temperature of its exfoliation is about 75 C higher than that for the studied sample of Hummers GO. It is suggested that higher exfoliation temperature and better crystallinity of GO are important factors for preparation of graphene powder using thermal exfoliation.

  • 1471.
    You, Shujie
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Sundqvist, Bertil
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Talyzin, Alexandr
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Enormous lattice expansion of hummers graphite oxide in alcohols at low temperatures2013Inngår i: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 7, nr 2, s. 1395-1399Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A structural study of swelling of Hummers graphite oxide (H-GO) in excess of liquid alcohols was performed as a function of temperature using synchrotron X-ray diffraction and revealed a strong “negative thermal expansion” effect. The increase of the distance between graphene oxide layers is explained by insertion of additional solvent upon cooling of the H-GO/solvent system. The interlayer distance of H-GO is found to increase gradually upon temperature decrease, reaching 19.4 and 20.6 Å at 140 K for methanol and ethanol, respectively. The gradual expansion of the H-GO lattice upon cooling corresponds to insertion of at least two additional solvent monolayers and can be described as osmotic swelling. This phenomenon is distinctly different from the solvation of Brodie graphite oxide (B-GO), which was found earlier to exhibit crystalline swelling: single-step insertion of an additional solvent monolayer at low temperatures. The enormous structural expansion of H-GO at low temperatures is suggested to be useful for solution-based intercalation of graphite oxide with relatively large molecules and the synthesis of various composite materials.

  • 1472.
    Younesi, Reza
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    Characterization of Reaction Products in the Li-O2 Battery Using Photoelectron Spectroscopy2012Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The rechargeable Li-O2 battery has attracted interest due to its high theoretical energy density (about 10 times better than today’s Li-ion batteries). In this PhD thesis the cycling instability of the Li-O2 battery has been studied. Degradation of the battery has been followed by studying the interface between the electrodes and electrolyte and determining the chemical composition and quantity of degradation products formed after varied cycling conditions. For this in-house and synchrotron based Photoelectron Spectroscopy (PES) were used as a powerful surface sensitive technique. Using these methods quantitative and qualitative information was obtained of both amorphous and crystalline compounds. To make the most realistic studies the carbon cathode pore structure was optimised by varying the binder to carbon ratio. This was shown to have an effect on improving the discharge capacity. For Li-O2 batteries electrolyte decomposition is a major challenge. The stability of different electrolyte solvents and salts were investigated. Aprotic carbonate and ether based solvents such as PC, EC/DEC, TEGDME, and PEGDME were found to decompose during electrochemical cycling of the cells. The carbonate based electrolytes decompose to form a 5-10 nm thick surface layer on the carbon cathode during discharge which was then removed during battery charging. The degradation products of the ether based electrolytes consisted mainly of ether and carbonate based surface species. It is also shown that Li2O2 as the final discharge product of the cell is chemically reactive and decomposes carbonate and ether based solvents. The stability of lithium electrolyte salts (such as LiPF6, LiBF4, LiB(CN)4, LiBOB, and LiClO4) was also studied. The PES results revealed that all salts are unstable during the cell cycling and in contact with Li2O2. Decomposition layers thinner than 5 nm were observed on Li2O2. Furthermore, it is shown that the stability of the interface on the lithium anode is a chief issue. When compared to Li batteries (where oxygen levels are below 10 ppm) working in the presence of excess oxygen leads to the decomposition of carbonate based electrolytes to a larger degree.

  • 1473.
    Younesi, Reza
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Brant, William
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Mogensen, Ronnie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Larsson, Paul
    ALTRIS AB.
    A Cheap and Sustainable Cathode Material for Sodium Ion Batteries2017Konferansepaper (Annet vitenskapelig)
  • 1474.
    Younesi, Reza
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Hahlin, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Björefors, Fredrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Johansson, Patrik
    Department of Applied Physics, Chalmers University of Technology.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Li-O2 Battery Degradation by Lithium Peroxide (Li2O2): A Model Study2013Inngår i: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 25, nr 1, s. 77-84Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The chemical stability of the Li-O2 battery components (cathode and electrolyte) in contact with lithiumperoxide (Li2O2) was investigated using X-ray photoelectron spectroscopy (XPS). XPS is a versatile method to detect amorphous as well as crystalline decomposition products of both salts and solvents. Two strategies were employed. First, cathodes including carbon, α‑MnO2 catalyst, and Kynar binder (PVdF-HFP) were exposed to Li2O2 and LiClO4 in propylenecarbonate (PC) or (tetraethylene glycol dimethyl ether) TEGDME electrolytes. The results indicated that Li2O2 degrades TEGDME to carboxylate containing species and that the decomposition products in turn degraded the Kynar binder. The α‑MnO2 catalyst was unaffected. Second, Li2O2 model surfaces were kept in contact with different electrolytes to investigate the chemical stability, and also the resulting surface layer on Li2O2. Further, the XPS experiments revealed that the Li salts LiPF6, LiBF4, and LiClO4 decomposed to form LiF or LiCl together with P-O or B-O bond containing compounds when exposed to Li2O2. PC decomposed to carbonate and ether based species. The degradation of the electrolytes increased from short to long exposure time indicating that the surface layer on Li2O2 became thicker by increasing time. Overall, it was shown that a mixture of ethylene carbonate and diethyl carbonate (EC/DEC) is more robust in contact with Li2O2 compared to PC.

  • 1475.
    Younesi, Reza
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Hahlin, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Surface Characterization of the Carbon Cathode and the Lithium Anode of Li-O2 Batteries using LiClO4 or LiBOB salts2013Inngår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 5, nr 4, s. 1333-1341Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The surface compositions of a MnO2 catalyst containing carbon cathode and a Li anode in a Li–O2 battery were investigated using synchrotron-based photoelectron spectroscopy (PES). Electrolytes comprising LiClO4 or LiBOB salts in PC or EC:DEC (1:1) solvents were used for this study. Decomposition products from LiClO4 or LiBOB were observed on the cathode surface when using PC. However, no degradation of LiClO4 was detected when using EC/DEC. We have demonstrated that both PC and EC/DEC solvents decompose during the cell cycling to form carbonate and ether containing compounds on the surface of the carbon cathode. However, EC/DEC decomposed to a lesser degree compared to PC. PES revealed that a surface layer with a thickness of at least 1–2 nm remained on the MnO2 catalyst at the end of the charged state. It was shown that the detachment of Kynar binder influences the surface composition of both the carbon cathode and the Li anode of Li–O2 cells. The PES results indicated that in the charged state the SEI on the Li anode is composed of PEO, carboxylates, carbonates, and LiClO4 salt.

  • 1476.
    Younesi, Reza
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Hahlin, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Roberts, Matthew
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    The SEI Layer Formed on Lithium Metal in the Presence of Oxygen: A Seldom Considered Component in the Development of the Li-O2 battery2013Inngår i: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 225, s. 40-45Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The SEI layer formed on metallic Li which has been used as an anode in a Li-O2 battery is studied for the first time. We have used XPS to monitor the surface composition of the lithium electrode and have identified the various chemical species present. The XPS results indicated that the composition of the SEI layer is affected by the presence of oxygen and is unstable during cycling. We also observed decomposition products from the binder material used in the cathode on the surface of the lithium anode. This new SEI layer has an increased resistance affecting the lithium deposition which is essential for battery operation.

  • 1477.
    Younesi, Reza
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Singh, Neelam
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Urbonaite, Sigita
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    The Primary Nonaqueous Lithium-Air Battery2009Konferansepaper (Annet vitenskapelig)
  • 1478.
    Younesi, Reza
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Urbonaite, Sigita
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    The Role of Carbon in the Cathode of a Li-O2 Battery2010Konferansepaper (Fagfellevurdert)
  • 1479.
    Younesi, S Reza
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Urbonaite, Sigita
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Björefors, Fredrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Influence of the Cathode Porosity on the Discharge Performance of the Lithium-Oxygen Battery2011Inngår i: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 196, nr 22, s. 9835-9838Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    By varying the ratio between the amount of carbon and Kynar binder in the cathode of a lithium-oxygen battery, it could be shown that an increasing amount of binder resulted in a decrease in the discharge capacity, mainly as a result of the decrease in the cathode porosity. It was shown that the Kynar binder blocked the majority of the pores with a width below 300 angstrom as determined by studying the pore volume and pore size distribution by nitrogen adsorption. Three carbonate based electrolytes (PC, PC:DEC (1:1), and EC:DEC (2:1) with 1 M LiPF(6)) were tested with the various cathode film compositions. Generally, the PC:DEC and EC:DEC based electrolytes provided higher capacities than PC. The results indicated that the air electrode composition and its effect on the porosity of the cathode, as well as electrolyte properties, are important when optimizing the discharge capacity.

  • 1480.
    Yu, Byoung-Soo
    et al.
    Kwangwoon University, South Korea.
    Jeon, Jun-Young
    Kwangwoon University, South Korea.
    Henry, Anne
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Ha, Tae-Jun
    Kwangwoon University, South Korea.
    Characteristics of Low-Temperature Solution-Processed Boron Nitride Thin Films for Flexible Nanoelectronics2017Inngår i: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 17, nr 11, s. 8567-8570Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, we demonstrate the characteristics of high quality boron nitride (BN) thin films for high performance 2 dimensional nanoelectronics. Such thin films were deposited using solution-process technology such as spin-coating, spraying and aerosol deposition at low temperature of 100 degrees C. The material properties of these BN thin films with optimized fabrication processes are competitive with those of BN deposited by employing the vacuum chemical vapor deposition technique. In order to characterize the material properties of solution-processed BN thin films, various measurements including atomic force microscopy, scanning electron microscopy, Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were performed. The optimized solution-process based on BN thin films are practical and reproducible in achieving high performance flexible nanoelectronics which require low process temperature and good uniformity in large-area.

  • 1481. Yu, F.
    et al.
    Li, F.
    Yao, T.
    Du, J.
    Liang, Y.
    Wang, Y.
    Han, H.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD. KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Fabrication and Kinetic Study of a Ferrihydrite-Modified BiVO4 Photoanode2017Inngår i: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 7, nr 3, s. 1868-1874Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In spite of great progress in the surface modification of semiconductor photoelectrodes, the role of the metal oxide cocatalyst on photoelectrochemical (PEC) performance is still not well understood. In this study, ferrihydrite (Fh) as a novel cocatalyst was decorated on a wormlike nanoporous BiVO4 photoanode. A surface kinetics study of Fh/BiVO4 by intensity-modulated photocurrent spectroscopy (IMPS) evidences the primary role of Fh on PEC performance enhancement, varying with the loading of Fh. It was found that dispersed Fh nanoparticles accelerate hole transfer for water oxidation, but the resulting photoanode suffers from poor stability. The thick layers of Fh address the stability of the electrode by suppressing surface charge recombination but result in reduced hole transfer rates. Modification of a BiVO4 film with optimally thick layers of discrete nanoflakes effectively reduces charge recombination without compromising stability, leading to a high AM 1.5 G photocurrent of 4.78 mA/cm2 at 1.23 V versus the reversible hydrogen electrode and an applied bias photon to current efficiency of 1.81% at 0.61 V. These values are comparable to the best results reported for undoped BiVO4. (Chemical Equation Presented).

  • 1482.
    Yu, Junchun
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Tonpheng, Bounphanh
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Gröbner, Gerhard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Andersson, Ove
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Microstructural and property changes in high pressure treated carbon nanotube/polybutadiene composites2011Inngår i: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 21, nr 35, s. 13672-13682Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In a comprehensive investigation of carbon nanotube (CNT) filled liquid and solid polybutadienes of molecular weights 2600 and 100000, respectively, we report results of thermal conductivity (κ), glass transition temperature (Tg), interfacial interaction and microstructure before and after simultaneous high-pressure and high-temperature (HP&HT) treatment. The HP&HT treatment changed polybutadiene from a liquid or solid to a highly cross-linked, ebonite-like, state. Concurrently, the microstructure changed from randomly dispersed CNTs to a web-like structure of coated and/or wrapped CNTs, with a permanent shift in their D*-band by as much as 16 cm−1. Moreover, κ of the recovered state of a 2.9 wt% –COOH functionalized multi-wall carbon nanotube (MWCNT) composite increased by 34% predominantly due to an irreversible densification and a consequentially increased phonon velocity. Results prior to treatment show that single-wall carbon nanotube (SWCNT) fillers promote κ better (17%/wt%) than –SH functionalized MWCNT fillers (8%/wt%), which is accounted for by their higher aspect ratio, whereas their about twice as high κ appears to be unimportant. The SWCNTs also raise Tg slightly more than MWCNTs and, in particular, under the most densified conditions and for the high molecular weight polybutadiene, which may be due to more favorable conditions for coating/wrapping.

  • 1483.
    Yu, Young-Sang
    et al.
    Lawrence Berkeley Natl Lab, Adv Light Source, Berkeley, CA 94720 USA.;Univ Illinois, Dept Chem, Chicago, IL 60607 USA..
    Farmand, Maryam
    Lawrence Berkeley Natl Lab, Adv Light Source, Berkeley, CA 94720 USA..
    Kim, Chunjoong
    Univ Illinois, Dept Chem, Chicago, IL 60607 USA.;Chungnam Natl Univ, Dept Mat Sci & Engn, Taejon 305764, Chungnam, South Korea..
    Liu, Yijin
    SLAC Natl Accelerator Lab, Stanford Synchrotron Radiat Lightsource, Menlo Pk, CA 94025 USA..
    Grey, Clare P.
    Univ Cambridge, Dept Chem, Lensfield Rd, Cambridge CB2 1EW, England.;SUNY Stony Brook, Dept Chem, Stony Brook, NY 11794 USA..
    Strobridge, Fiona C.
    Univ Cambridge, Dept Chem, Lensfield Rd, Cambridge CB2 1EW, England..
    Tyliszczak, Tolek
    Lawrence Berkeley Natl Lab, Adv Light Source, Berkeley, CA 94720 USA..
    Celestre, Rich
    Lawrence Berkeley Natl Lab, Adv Light Source, Berkeley, CA 94720 USA..
    Denes, Peter
    Lawrence Berkeley Natl Lab, Adv Light Source, Berkeley, CA 94720 USA..
    Joseph, John
    Lawrence Berkeley Natl Lab, Div Engn, Berkeley, CA 94720 USA..
    Krishnan, Harinarayan
    Lawrence Berkeley Natl Lab, Computat Res Div, Berkeley, CA 94720 USA..
    Maia, Filipe R.N.C.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för cell- och molekylärbiologi, Molekylär biofysik.
    Kilcoyne, A. L. David
    Lawrence Berkeley Natl Lab, Adv Light Source, Berkeley, CA 94720 USA..
    Marchesini, Stefano
    Lawrence Berkeley Natl Lab, Adv Light Source, Berkeley, CA 94720 USA..
    Leite, Talita Perciano Costa
    Lawrence Berkeley Natl Lab, Computat Res Div, Berkeley, CA 94720 USA..
    Warwick, Tony
    Lawrence Berkeley Natl Lab, Adv Light Source, Berkeley, CA 94720 USA..
    Padmore, Howard
    Lawrence Berkeley Natl Lab, Adv Light Source, Berkeley, CA 94720 USA..
    Cabana, Jordi
    Univ Illinois, Dept Chem, Chicago, IL 60607 USA..
    Shapiro, David A.
    Lawrence Berkeley Natl Lab, Adv Light Source, Berkeley, CA 94720 USA..
    Three-dimensional localization of nanoscale battery reactions using soft X-ray tomography2018Inngår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 9, artikkel-id 921Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Battery function is determined by the efficiency and reversibility of the electrochemical phase transformations at solid electrodes. The microscopic tools available to study the chemical states of matter with the required spatial resolution and chemical specificity are intrinsically limited when studying complex architectures by their reliance on two-dimensional projections of thick material. Here, we report the development of soft X-ray ptychographic tomography, which resolves chemical states in three dimensions at 11 nm spatial resolution. We study an ensemble of nano-plates of lithium iron phosphate extracted from a battery electrode at 50% state of charge. Using a set of nanoscale tomograms, we quantify the electrochemical state and resolve phase boundaries throughout the volume of individual nanoparticles. These observations reveal multiple reaction points, intra-particle heterogeneity, and size effects that highlight the importance of multi-dimensional analytical tools in providing novel insight to the design of the next generation of high-performance devices.

  • 1484.
    Yu, Ze
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Oorganisk kemi (stängd 20110630).
    Najafabadi, Hussein Moien
    KTH, Skolan för kemivetenskap (CHE), Kemi, Oorganisk kemi (stängd 20110630).
    Xu, Yunhua
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Nonomura, Kazuteru
    KTH, Skolan för kemivetenskap (CHE), Kemi, Oorganisk kemi (stängd 20110630).
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Kloo, Lars
    KTH, Skolan för kemivetenskap (CHE), Kemi, Oorganisk kemi (stängd 20110630).
    Ruthenium sensitizer with a thienylvinylbipyridyl ligand for dye-sensitized solar cells2011Inngår i: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 40, nr 33, s. 8361-8366Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new ruthenium bipyridyl complex, coded as YX360, incorporating a conjugated thienylvinylbipyridyl ligand, cis-Ru(dtbpy)(dcbpy)(NCS)(2) [dtbpy = 4,4'-di(thienylvinyl)-2,2'-bipyridyl; dcbpy = 4,4'-dicarboxy-2,2'-bipyridyl], has been synthesized and studied as a dye in dye-sensitized solar cells (DSCs). The new dye is compared to its precursor N719, which is one of the best ruthenium-based sensitizers known so far. In the dye YX360 the lowest metal-to-ligand charge-transfer (MLCT) band is red-shifted by 10 nm and the molar extinction coefficient is dramatically increased as compared to N719. The reason can largely be attributed to the introduction of the extended pi-conjugation unit to the ruthenium complex. Correspondingly, the incident photon-to-current conversion efficiency (IPCE) spectra of solar cells containing the dye YX360 show relatively higher values in the plateau region and a wider absorption spectrum relative to those of the dye N719. The effect is most pronounced for thinner TiO(2) films, for which comparable overall conversion efficiencies were obtained. However, as the TiO(2) film thickness is increased, DSCs containing N719 show superior conversion efficiencies. Although YX360 typically renders better short-circuit currents, the open-circuit voltage is suppressed because of larger electron recombination losses at the TiO(2)/dye/electrolyte interface. The results highlight that an extended aromatic ligand system in a sensitizing dye on the one hand improved light absorption, but on the other hand more efficiently loses photoelectrons through a recombination pathway via the dye to the electrolyte.

  • 1485.
    Yuan, Jianyu
    et al.
    Soochow University, Peoples R China.
    Guo, Wenping
    Fudan University, Peoples R China.
    Xia, Yuxin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Ford, Michael J.
    University of Calif Santa Barbara, CA 93106 USA; University of Calif Santa Barbara, CA 93106 USA.
    Jin, Feng
    Fudan University, Peoples R China.
    Liu, Dongyang
    Soochow University, Peoples R China.
    Zhao, Haibin
    Fudan University, Peoples R China.
    Inganäs, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Bazan, Guillermo C.
    University of Calif Santa Barbara, CA 93106 USA; University of Calif Santa Barbara, CA 93106 USA.
    Ma, Wanli
    Soochow University, Peoples R China.
    Comparing the device physics, dynamics and morphology of polymer solar cells employing conventional PCBM and non-fullerene polymer acceptor N22002017Inngår i: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 35, s. 251-262Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Current all polymer solar cells still suffer from low fill factors (FF) and short-circuit current density (J(sc)) compared with the conventional polymer/fullerene system. Herein in this work, devices using PTP8 as the electron donor and [70]PCBM as well as widely used polymer N2200 as the electron acceptor were systematically studied and compared. The major loss mechanisms in the all polymer solar cells were investigated to understand their relatively lower performance than the PTP8/fullerene system. By performing in-depth analysis on ultrafast transient transmission spectroscopy results, we estimated that in PTP8/N2200 device nearly half of the charges recombine geminately, which is confirmed as the major factor hindering the device performance of all polymer solar cells compared with polymer/fullerene system. Through thorough morphology analysis, the low charge generation efficiency is attributed to the reduced crystallinity of N2200 in the blend film and the unfavorable face-to-edge orientation at the donor/acceptor heterojunction. Coupling these results with knowledge from efficient polymer/fullerene systems, the future design of new polymers can devote to increase the attraction between the pi face of donor and acceptor, leading to enhanced face-to-face orientation at the heterojunction, while maintaining a high pi-pi stacking order for each polymer.

  • 1486.
    Yuan, Kang
    et al.
    Beijing General Research Institute of Mining and Metallurgy, Beijing, China.
    Jonnalagadda, Krisha Praveen
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Yu, Yueguang
    Beijing General Research Institute of Mining and Metallurgy, Beijing, China.
    Peng, Ru Lin
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Li, Xin-Hai
    Department of Management and Engineering, Linköping University, S.
    Ji, Xiaojuan
    Beijing General Research Institute of Mining and Metallurgy, Beijing, China.
    Shen, Jie
    Beijing General Research Institute of Mining and Metallurgy, Beijing, China.
    Thermal fatigue failure of thermal barrier coatings with a high-Cr MCrAIY bond coat2016Inngår i: Proceedings of the International Thermal Spray Conference (ITSC), 2016, Vol. 324, s. 273-278Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Thermal barrier coatings (TBCs) were air-plasma sprayed onto Hastelloy X substrates. The TBCs consisted of a high-Cr MCrAlY (M for Ni and Co) bond coat and a yttria-stabilized zirconia (YSZ) top coat. The TBC samples were thermally cycled between 100 ºC and 1100 ºC with 1 hour dwell time at 1100 ºC. The thermal fatigue failure of the TBCs was investigated via microstructure analyses. The final fatigue failure of the TBCs was caused by the formation of interface-parallel cracks in the YSZ top coat. The formation of the cracks was found to be strongly related to the oxidation behaviour of the MCrAlY bond coat. The development of the oxide layers was therefore studied in detail. A thermokinetic model was also used to deepen the understanding on the elemental diffusion behavior in the materials.

  • 1487. Yuan, Y.
    et al.
    Greuner, H.
    Boeswirth, B.
    Linsmeier, Ch.
    Luo, G. -N
    Fu, B. Q.
    Xu, H. Y.
    Shen, Zhijian James
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för materialkemi.
    Liu, W.
    Surface modification of molten W exposed to high heat flux helium neutral beams2013Inngår i: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 437, nr 1-3, s. 297-302Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    High heat flux tests with central heat flux of 10.5 MW/m(2) using helium neutral beams have been carried out on rolled tungsten. The energy of helium particles is 33 keV and the particle flux is 2 x 10(21) m(-2) s(-1). An 80 x 65 x 3 mm(3) rolled tungsten plate is firstly exposed to a 4.6 s pulse resulting in partially molten surfaces. Thereafter the tungsten plate is irradiated by several helium pulses with fluences of 1.2-2.5 x 10(22)/m(2) and peak temperatures from 1450 to 2590 degrees C. The experiments show that: (1) helium-induced surface modification of the resolidified tungsten surface is very different from that of the non-molten surface; (2) the surface morphology of molten surface is closely related to the orientation of the resolidified grain; (3) the evolution of surface modifications, for both of the molten and non-molten tungsten surfaces, indicates a strong dependence on the surface temperature and local helium fluence.

  • 1488.
    Yuan, Zhongcheng
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten. Soochow University, Peoples R China.
    Yang, Yingguo
    Chinese Academic Science, Peoples R China.
    Wu, Zhongwei
    Soochow University, Peoples R China.
    Bai, Sai
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Xu, Weidong
    Soochow University, Peoples R China.
    Song, Tao
    Soochow University, Peoples R China.
    Gao, Xingyu
    Chinese Academic Science, Peoples R China.
    Gao, Feng
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Sun, Baoquan
    Soochow University, Peoples R China.
    Approximately 800-nm-Thick Pinhole-Free Perovskite Films via Facile Solvent Retarding Process for Efficient Planar Solar Cells2016Inngår i: ACS APPLIED MATERIALS and INTERFACES, ISSN 1944-8244, Vol. 8, nr 50, s. 34446-34454Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Device performance of organometal halide perovskite solar cells significantly depends on the quality and thickness of perovskite absorber films. However, conventional deposition methods often generate pinholes within similar to 300 nm-thick perovskite films, which are detrimental to the large area device manufacture. Here we demonstrated a simple solvent retarding process to deposit uniform pinhole free perovskite films with thicknesses up to similar to 800 nm. Solvent evaporation during the retarding process facilitated the components separation in the mixed halide perovskite precursors, and hence the final films exhibited pinhole free morphology and large grain sizes. In addition, the increased precursor concentration after solvent-retarding process led to thick perovskite films. Based on the uniform and thick perovskite films prepared by this convenient process, a champion device efficiency up to 16.8% was achieved. We believe that this simple deposition procedure for high quality perovskite films around micrometer thickness has a great potential in the application of large area perovskite solar cells and other optoelectronic devices.

  • 1489.
    Yun, Sang Ho
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Dibos, A.
    Lee, Hyung-Seok
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Wu, J. Z.
    Karlsson, Ulf O.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Growth of boron nano-junctions2006Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 252, nr 15, s. 5587-5589Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, we demonstrate the synthesis of various types of boron nanowire junctions in a self-assembled manner by simple closed-tube thermal vapor transfer method. The Y-type boron nano-junctions and lateral boron-silicon alloy nano-junctions were grown on Si substrates, based on the oxide assisted VLS growth mode at a relatively low processing temperature regime and the VLS growth mode at the high processing temperature regime, respectively.

  • 1490. Zadin, Vahur
    et al.
    Brandell, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Electrochemical simulations of 3D-battery architectures2015Inngår i: SolidState Battery Handbook / [ed] Nancy J. Dudney, William C West, Jagjit Nanda, Singapore: World Scientific , 2015, 2, s. 731-777Kapittel i bok, del av antologi (Fagfellevurdert)
  • 1491. Zakharova, IB
    et al.
    Donenko, EA
    Biryulin, YF
    Sharonova, LV
    Makarova, Tatiana
    Optical and vibrational properties of thin film Fullerene-Zn(II) tetraphenylporphyrin complexes2008Inngår i: Fullerenes, nanotubes, and carbon nanostructures (Print), ISSN 1536-383X, E-ISSN 1536-4046, Vol. 16, nr 5-6, s. 424-429Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work a novel material, fullerene-Zn(II) tetraphenylporphyrin, is obtained and studied using UV-Vis-NIR absorption and Raman scattering methods. C-60-ZnTPP thin films were produced by vacuum evaporation in hot-wall reactor. The detection of the A(g2)-derived modes at 1460 and 1452cm(-1) in the Raman spectra manifests the charge-transfer C-60-ZnTPP complex formation. It is shown that additional absorption band at 1.38-1.53 eV observed in the films corresponds to the HOMO-LUMO gap of C-60-ZnTPP complex.

  • 1492. Zamora, V.
    et al.
    Ortiz, A. L.
    Guiberteau, F.
    Nygren, Mats
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Crystal-size dependence of the spark-plasma-sintering kinetics of ZrB2 ultra-high-temperature ceramics2012Inngår i: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 32, nr 2, s. 271-276Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The crystal-size dependence of the spark-plasma-sintering (SPS) kinetics of ZrB2 ultra-high-temperature ceramics (UHTCs) was investigated. It was found that refining the starting powder enhances the SPS kinetics, reducing the onset temperatures of sintering and of the intermediate and final sintering regimes, as well as promoting a greater maximum shrinkage rate at lower temperatures. This enhancement was only relevant with reduction in crystal size to the nanoscale. Finally, the implications for low-temperature sintering of ZrB2 UHTCs are discussed.

  • 1493. Zamora, Victor
    et al.
    Nygren, Mats
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Guiberteau, Fernando
    Ortiz, Angel L.
    Effect of graphite addition on the spark-plasma sinterability of ZrB2 and ZrB2-SiC ultra-high-temperature ceramics2014Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 40, nr 7, s. 11457-11464Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of a 2 wt% addition of particulate graphite on the spark-plasma sintering (SPS) kinetics of both ZrB2 and ZrB2+30 vol% SiC was investigated using to that end two broad sets of powder mixtures prepared by high-energy co-ball-milling. It was observed that the particulate graphite addition enhances the SPS kinetics of both systems, and it was identified that, contrary to the case in conventional sintering, this improvement in sinterability is not due to the carbothermal reduction of oxides in situ during SPS but to the lubrication imposed by the graphite flakes inducing a greater green-body densification. Consequently, the graphite is not consumed during SPS but remains in the microstructure of the resulting ultra-high-temperature ceramics (UHTCs) as flaky particles dispersed homogeneously at grain boundaries. Implications of interest for the UHTC community are discussed.

  • 1494. Zamora, Victor
    et al.
    Ortiz, Angel L.
    Guiberteau, Fernando
    Nygren, Mats
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    In situ formation of ZrB2-ZrO2 ultra-high-temperature ceramic composites from high-energy ball-milled ZrB2 powders2012Inngår i: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 518, s. 38-43Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The in situ formation is reported of a fine-grained ZrB2 ultra-high-temperature ceramic (UHTC) containing evenly distributed ZrO2 of uniform size located at triple joints and grain boundaries of the ZrB2 grains, discovered during the spark-plasma sintering of ZrB2 powders subjected to high-energy ball-milling in air. It is found that this type of microstructure forms because the oxide film of ZrO2, developed on the surface of the ZrB2 particles during the high-energy ball-milling in air, creeps towards the ZrB2 multigrain joints under the application of pressure during sintering, and then crystallizes there during the fast cooling down to room-temperature. Together with the mechanism by which these dense ZrB2-ZrO2 UHTC composites form, it is also shown that they are simultaneously harder and much tougher than their ZrB2 monolith counterpart.

  • 1495. Zamora, Victor
    et al.
    Ortiz, Angel L.
    Guiberteau, Fernando
    Nygren, Mats
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    On the enhancement of the spark-plasma sintering kinetics of ZrB2-SiC powder mixtures subjected to high-energy co-ball-milling2013Inngår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 39, nr 4, s. 4191-4204Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The spark-plasma sintering (SPS) kinetics of ZrB2-SiC powder mixtures was investigated as a function of the degree of high-energy co-ball-milling and of the SiC content (5, 17.5, or 30 vol%). As in ZrB2 without SiC, it was found that the crystal size refinement induced by the continued milling progressively enhances the SPS kinetics of ZrB2-SiC, again only moderately if the refinement is to the ultra-fine range, but very marked if the refinement is to the nanoscale. It was also found that the SiC addition further enhances the SPS kinetics of ZrB2, although the improvement did not scale directly with the SiC content, and became less relevant with the refinement of the ZrB2 crystal sizes to the nanoscale. The improved kinetics induced by the SiC addition was identified as being due to the formation of amorphous borosilicate from the oxide passivating layers on the ZrB2 and SiC particles. This not only speeds up the interparticle diffusion, but also it is segregated under the application of pressure into the multi-grain joints, filling pores. The enhanced kinetics induced by the progressive milling is due to the continuous reduction of the diffusion distances and to the development of a greater density of grain boundaries available as faster diffusion paths, together with the greater formation of amorphous borosilicate. Implications of interest for the ultra-high-temperature ceramics community are discussed.

  • 1496. Zander, Thomas
    et al.
    Wieland, Florian
    Raj, Akanksha
    Wang, Min
    Nowak, Benedikt
    Krywka, Christina
    Dédinaité, Andra A
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Life Science. KTH Royal Institute of Technology, School of Chemical Sciences and Engineering, Department of Chemistry, Surface and Corrosion Science.
    Claesson, Per M.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik. Department of Chemistry Surface and Corrosion Science, KTH Royal Institute of Technology.
    Garamus, Vasil M.
    Schreyer, Andreas
    Willumeit-Römer, Regine
    The influence of hyaluronan on the structure of a DPPC-bilayer under high pressures2016Inngår i: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 142, s. 230–238-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The superior lubrication properties of synovial joints have inspired many studies aiming at uncovering the molecular mechanisms which give rise to low friction and wear. However, the mechanisms are not fully understood yet, and, in particular, it has not been elucidated how the biolubricants present at the interface of cartilage respond to high pressures, which arise during high loads of joints. In this study we utilize a simple model system composed of two biomolecules that have been implied as being important for joint lubrication. It consists of a solid supported dipalmitoylphosphatidylcholin (DPPC) bilayer, which was formed via vesicles fusion on a flat Si wafer, and the anionic polysaccharide hyaluronan (HA). We first characterized the structure of the HA layer that adsorbed to the DPPC bilayers at ambient pressure and different temperatures using X-ray reflectivity (XRR) measurements. Next, XRR was utilized to evaluate the response of the system to high hydrostatic pressures, up to 2 kbar (200 MPa), at three different temperatures. By means of fluorescence microscopy images the distribution of DPPC and HA on the surface was visualized. Our data suggest that HA adsorbs to the headgroup region that is oriented towards the water side of the supported bilayer. Phase transitions of the bilayer in response to temperature and pressure changes were also observed in presence and absence of HA. Our results reveal a higher stability against high hydrostatic pressures for DPPC/HA composite layers compared to that of the DPPC bilayer in absence of HA.

  • 1497. Zavodnik, Valery E.
    et al.
    Ivanov, Sergey A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Stash, Adam I.
    alpha-lead tellurite from single-crystal data2008Inngår i: Acta Crystallographica Section E: Structure Reports Online, ISSN 1600-5368, E-ISSN 1600-5368, Vol. 64, s. I16-U10Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The crystal structure of the title compound, alpha-PbTeO3 ( PTO), has been reported previously by Mariolacos [ Anz. Oesterr. Akad. Wiss. Math. Naturwiss. Kl. ( 1969), 106, 128-130], refined on powder data. The current determination at room temperature from data obtained from single crystals grown by the Czochralski method shows a significant improvement in the precision of the geometric parameters when all atoms have been refined anisotropically. The selection of a centrosymmetric (C2/c) structure model was confirmed by the second harmonic generation test. The asymmetric unit contains three formula units. The structure of PTO is built up of three types of distorted [PbOx] polyhedra (x=7 and 9) which share their O atoms with TeO3 pyramidal units. These main anionic polyhedra are responsible for establishing the two types of tunnel required for the stereochemical activity of the lone pairs of the Pb2+ and Te4+ cations.

  • 1498.
    Zeglio, Erica
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Self-doped Conjugated Polyelectrolytes for Bioelectronics Applications2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Self-doped conjugated polyelectrolytes (CPEs) are a class of conducting polymers constituted of a π-conjugated backbone and charged side groups. The ionic groups provide the counterions needed to balance the charged species formed in the CPEs backbones upon oxidation. As a result, addition of external counterions is not required, and the CPEs can be defined as selfdoped. The combination of their unique optical and electrical properties render them the perfect candidates for optoelectronic applications. Additionally, their “soft” nature provide for the mechanical compatibility necessary to interface with biological systems, rendering them promising materials for bioelectronics applications. CPEs solubility, aggregation state, and optoelectronic properties can be easily tuned by different means, such as blending or interaction with oppositely charged species (such as surfactants), in order to produce materials with the desired properties. In this thesis both the strategies have been explored to produce new functional materials that can be deposited to form a thin film and,  therefore, used as an active layer in organic electrochemical transistors (OECTs). Microstructure formation of the films as well as influence on devices operation and performance have been investigated. We also show that these methods can be exploited to produce materials whose uniquecombination of self-doping ability and hydrophobicity allows incorporation into the phospholipid double layer of biomembranes, while retaining their properties. As a result, self-doped CPEs can be used both as sensing elements to probe the physical state of biomembranes, and as functional ones providing them with new functionalities, such as electrical conductivity. Integration of conductive electronic biomembranes into OECTs devices has brought us one step forward on the interface of manmade technologies with biological systems.

  • 1499.
    Zeglio, Erica
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Schmidt, Martina M.
    University of Bayreuth, Germany.
    Thelakkat, Mukundan
    University of Bayreuth, Germany.
    Gabrielsson, Roger
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Soling, Niclas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Inganäs, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Conjugated Polyelectrolyte Blends for Highly Stable Accumulation Mode Electrochemical Transistors2017Inngår i: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 29, nr 10, s. 4293-4300Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Counterion exchange has been introduced as a method to modify properties of anionic conjugated poly electrolyte (CPE) blends. Blending of two self-doped CPEs having metallic and semiconducting behavior has been achieved from two different solvents, by exchanging the counterion of the metallic component. Different blending conditions lead to films exhibiting different optical properties, depending on the aggregation states of the CPEs. Conductance responses for the blends showed the opportunity to tune threshold voltage of the films both by blending and counterion exchange. Therefore, the blends have been exploited for the fabrication of accumulation mode organic electrochemical transistors. These devices exhibit short switching times and high transconductance, up to 15.3 rnS, as well as high stability upon fast pulsed cycles, retaining 88% of the drain currents after 2 x 10(3) cycles.

  • 1500.
    Zeglio, Erica
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Vagin, Mikhail
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Musumeci, Chiara
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Ajjan, Fátima
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Gabrielsson, Roger
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    Trinh, Xuan thang
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Nguyen, Son Tien
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Maziz, Ali
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biosensorer och bioelektronik. Linköpings universitet, Tekniska fakulteten.
    Solin, Niclas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Inganäs, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Conjugated Polyelectrolyte Blends for Electrochromic and Electrochemical Transistor Devices2015Inngår i: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 27, nr 18, s. 6385-6393Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two self-doped conjugated polyelectrolytes, having semiconducting and metallic behaviors, respectively, have been blended from aqueous solutions in order to produce materials with enhanced optical and electrical properties. The intimate blend of two anionic conjugated polyelectrolytes combine the electrical and optical properties of these, and can be tuned by blend stoichiometry. In situ conductance measurements have been done during doping of the blends, while UV vis and EPR spectroelectrochemistry allowed the study of the nature of the involved redox species. We have constructed an accumulation/depletion mode organic electrochemical transistor whose characteristics can be tuned by balancing the stoichiometry of the active material.

272829303132 1451 - 1500 of 1563
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf