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  • 1851. Zhou, Xin
    et al.
    Wang, Dianzheng
    Liu, Xihe
    Zhang, DanDan
    Qu, Shilian
    Ma, Jing
    London, Gary
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Tsinghua University, China.
    Liu, Wei
    3D-imaging of selective laser melting defects in a Co-Cr-Mo alloy by synchrotron radiation micro-CT2015In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 98, p. 1-16Article in journal (Refereed)
    Abstract [en]

    Microstructure defects set the mechanical property limits for solid Co-Cr-Mo alloy prepared by selective laser melting (SLM). Previous studies were mainly based on 2D SEM images and thus not able to provide information of the 3D morphologies of the complex defects. In this paper, the remaining porosities in Co-Cr-Mo alloy parts prepared by selective laser melting were presented in relation to the laser processing parameters. In order to understand the defect forming mechanism, accurate 3D images of defects inside SLM fabricated Co-Cr-Mo samples were provided by synchrotron radiation micro-CT imaging of 300 pm thick slices cut from a 10 mm cube. With 3D reconstructed images distinctive morphologies of SLM defects spanning across the consolidated powder layers were generated. The faults can be classified as single layer or multi-layers defects. The accidental single layer defects form as gaps between adjacent laser melt tracks or melt track discontinuousness caused by inherent fluid instability under various disturbances. The first formed single layer defect generates often a multi-layer defect spanning for 2-3 subsequent powder layers. By stabilizing the melt pool flow and by reducing the surface roughness through adjusting processing parameters it appears possible to reduce the defect concentrations.

  • 1852. Zhou, Yaxin
    et al.
    Saito, Tsuguyuki
    Bergstrom, Lennart
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). The University of Tokyo, Japan.
    Isogai, Akira
    Acid-Free Preparation of Cellulose Nanocrystals by TEMPO Oxidation and Subsequent Cavitation2018In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, no 2, p. 633-639Article in journal (Refereed)
    Abstract [en]

    Softwood bleached kraft pulp (SBKP) and microcrystalline cellulose (MCC) were oxidized using a 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated system. The TEMPO-oxidized SBKP prepared with 10 mmol/g NaClO (SBKP-10) had a higher mass recovery ratio and higher carboxylate content than the other prepared celluloses including the TEMPO-oxidized MCCs. The SBKP-10 was then exposed to cavitation-induced forces through sonication in water for 10-120 min to prepare aqueous dispersions of needle-like TEMPO-oxidized cellulose nanocrystals (TEMPO-CNCs) with homogeneous width of 3.5 to 3.6 nm and average lengths of similar to 200 nm. The average chain lengths of the cellulose molecules that make up the TEMPO-CNCs were less than half the average lengths of the TEMPO-CNCs. Compared with conventional CNCs prepared by acid hydrolysis, the TEMPO-CNCs prepared by the acid-free and dialysis-free process exhibited higher mass recovery ratios, significantly higher amounts of surface anionic groups, and smaller and more homogeneous widths.

  • 1853.
    Zhu, Chuantao
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nanocellulose and Its Biohybrids for Water Purification: Atomic Force Microscopy as a Tool to Probe Surface Properties and Interactions2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Nanocellulose has been explored extensively in recent years as an adsorbent due to its promising performance in the removal of charged contaminants from water. In this thesis, various atomic force microscopy (AFM) techniques are used to understand the surface characteristics and specific interactions of nanocellulose with water contaminants (heavy metal ions and dyes) and nanoscale entities (Graphene Oxide (GO) and Graphene Oxide nanocolloids (nanoGO)), and explain the mechanisms related to adsorption, metal ion clustering, self-assembly and mechanical reinforcement.

    AFM probes functionalised with microscale and nanoscale celluloses were used as colloidal probes to study specific surface interactions with heavy metal ions and dyes in the aqueous medium. This approach enabled quantitative measurements of the adhesion force between nanocellulose and the water pollutants under in situ conditions by direct or in-direct methods. Adhesion forces, including the piconewton range, were measured, and the forces depended on the surface groups present on the nanocellulose.

    AFM imaging in dry and/or wet conditions was successfully used to investigate the adsorption, self-assembly, morphology and mechanical properties of nanocellulose and its bio-hybrids. The self-assembly, the metal nanolayer and the nanoclusters on the surface of nanocellulose and its biohybrids after adsorption were confirmed and explained by advanced microscopy, spectroscopy and computational modelling.

    The adhesion and stiffness measurement of single nanocellulose fibers using in situ PeakForce Quantitative Nanomechanical (PF-QNM) characterization confirmed the adsorption of metal ions on the surface in the liquid medium. PF-QNM mapping of the freestanding biohybrid membranes also revealed the enhanced modulus of the biohybrid membrane compared with the TEMPO(2,2,6,6-tetramethylpiperidine-1-oxylradical)-mediated oxidation nanofibers (TOCNF) membrane, which explained the hydrolytic stability and recyclability of these membranes.

    The established methodology, which combines advanced microscopy with spectroscopy and modelling techniques, can be extended to other biobased macromolecular systems to investigate the adsorption behaviour and/or surface interactions in bio nanotechnology.

  • 1854.
    Zhu, Chuantao
    et al.
    Luleå University of Technology, Sweden.
    Dobryden, Illia
    Rydén, Jens
    Öberg, Sven
    Holmgren, Allan
    Mathew, Aji P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Luleå University of Technology, Sweden.
    Adsorption Behavior of Cellulose and Its Derivatives toward Ag(I) in Aqueous Medium: An AFM, Spectroscopic, and DFT Study2015In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 31, no 45, p. 12390-12400Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to develop a fundamental understanding of the adsorption behavior of metal ions on cellulose surfaces using experimental techniques supported by computational modeling, taking Ag(I) as an example. Force interactions among three types of cellulose microspheres (native cellulose and its derivatives with sulfate and phosphate groups) and the silica surface in AgNO3 solution were studied with atomic force microscopy (AFM) using the colloidal probe technique. The adhesion force between phosphate cellulose microspheres (PCM) and the silica surface in the aqueous AgNO3 medium increased significantly with increasing pH while the adhesion force slightly decreased for sulfate cellulose microspheres (SCM), and no clear adhesion force was observed for native cellulose microspheres (CM). The stronger adhesion enhancement for the PCM system is mainly attributed to the electrostatic attraction between Ag(I) and the negative silica surface. The observed force trends were in good agreement with the measured zeta potentials. The scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) analyses confirmed the presence of silver on the surface of cellulose microspheres after adsorption. This study showed that PCM with a high content of phosphate groups exhibited a larger amount of adsorbed A(I) than CM and SCM and possible clustering of Ag(I) to nanoparticles. The presence of the phosphate group and a wavenumber shift of the P-OH vibration caused by the adsorption of silver ions on the phosphate groups were further confirmed with computational studies using density functional theory (DFT), which gives support to the above findings regarding the adsorption and clustering of Ag(I) on the cellulose surface decorated with phosphate groups as well as IR spectra.

  • 1855.
    Zhu, Chuantao
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Liu, Peng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Mathew, Aji P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Self-Assembled TEMPO Cellulose Nanofibers: Graphene Oxide-Based Biohybrids for Water Purification2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 24, p. 21048-21058Article in journal (Refereed)
    Abstract [en]

    Nanocellulose, graphene oxide (GO), and their combinations there off have attracted great attention for the application of water purification recently because of their unique adsorption capacity, mechanical characteristics, coordination with transition metal ions, surface charge density, and so on. In the current study, (2,2,6,6-tetramethylpiperidine-1-oxylradical) (TEMPO)-mediated oxidized cellulose nanofibers (TOCNF) and GO sheets or graphene oxide nanocolloid (nanoGO) biohybrids were prepared by vacuum filtration method to obtain self-assembled adsorbents and membranes for water purification. The porous biohybrid structure, studied using advanced microscopy techniques, revealed a unique networking and self-assembling of TOCNF, GO, and nanoGO, driven by the morphology of the GO phase and stabilized by the intermolecular H-bonding between carboxyl groups and hydroxyl groups. The biohybrids exhibited a promising adsorption capacity toward Cu(II) due to TOCNF and formed a unique arrested state in water because of ionic cross-linking between adsorbed Cu(II) and the negatively charged TOCNF and GO phase. The mechanical performance of the freestanding biohybrid membranes investigated using PeakForce Quantative NanoMechanics characterization confirmed the enhanced modulus of the hybrid membrane compared to that of the TOCNF membrane. Besides, the TOCNF+nanoGO membrane shows unique hydrolytic stability and recyclability even under several cycles of adsorption and desorption and strong sonication. This study shows that TOCNF and nanoGO hybrids can generate new water-cleaning membranes with synergistic properties because of their high adsorption capacity, flexibility, hydrolytic stability, and mechanical robustness.

  • 1856.
    Zhu, Chuantao
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Mathew, Aji P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nanocellulose-Functionalized AFM Probes for Investigating Surface Interactions by Force SpectroscopyManuscript (preprint) (Other academic)
  • 1857.
    Zhu, Chuantao
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Monti, Susanna
    Mathew, Aji P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Cellulose Nanofiber-Graphene Oxide Biohybrids: Disclosing the Self-Assembly and Copper-Ion Adsorption Using Advanced Microscopy and ReaxFF Simulations2018In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 12, no 7, p. 7028-7038Article in journal (Refereed)
    Abstract [en]

    The self-assembly of nanocellulose and graphene oxide into highly porous biohybrid materials has inspired the design and synthesis of multifunctional membranes for removing water pollutants. The mechanisms of self-assembly, metal ion capture, and cluster formation on the biohybrids at the nano- and molecular scales are quite complex. Their elucidation requires evidence from the synergistic combination of experimental data and computational models. The AFM-based microscopy studies of (2,2,6,6-tetramethylpiperidine-l-oxylradical)-mediated oxidized cellulose nanofibers (TOCNFs), graphene oxide (GO), and their biohybrid membranes provide strong, direct evidence of self-assembly; small GO nanoparticles first attach and accumulate along a single TOCNF fiber, while the long, flexible TOCNF filaments wrap around the flat, wide GO planes, thus forming an amorphous and porous biohybrid network. The layered structure of the TOCNFs and GO membrane, derived from the self-assembly and its surface properties before and after the adsorption of Cu(II), is investigated by advanced microscopy techniques and is further clarified by the ReaxFF molecular dynamics (MD) simulations. The dynamics of the Cu(II)-ion capture by the TOCNF and GO membranes in solution and the ion cluster formation during drying are confirmed by the MD simulations. The results of this multidisciplinary investigation move the research one step forward by disclosing specific aspects of the self-assembly behavior of biospecies and suggesting effective design strategies to control the pore size and robust materials for industrial applications.

  • 1858.
    Zhu, Chuantao
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Monti, Susanna
    Mathew, Aji P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    TEMPO Cellulose Nanofiber - Graphene Oxide Biohybrids: Disclosing Self-Assembly and Cu(II) Adsorption using Advanced Microscopy and ReaxFF Molecular Dynamics SimulationsManuscript (preprint) (Other academic)
  • 1859.
    Zhu, Chuantao
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Luleå University of Technology, Sweden.
    Soldatov, Alexander
    Mathew, Aji P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Luleå University of Technology, Sweden.
    Advanced microscopy and spectroscopy reveal the adsorption and clustering of Cu(II) onto TEMPO-oxidized cellulose nanofibers2017In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 9, no 22, p. 7419-7428Article in journal (Refereed)
    Abstract [en]

    TEMPO (2,2,6,6-tetramethylpiperidine-1-oxylradical)-mediated oxidation nanofibers (TOCNF), as a biocompatible and bioactive material, have opened up a new application of nanocellulose for the removal of water contaminants. This development demands extremely sensitive and accurate methods to understand the surface interactions between water pollutants and TOCNF. In this report, we investigated the adsorption of metal ions on TOCNF surfaces using experimental techniques atthe nano and molecular scales with Cu(II) as the target pollutant in both aqueous and dry forms. Imaging with in situ atomic force microscopy (AFM), together with a study of the physiochemical properties of TOCNF caused by adsorption with Cu(II) in liquid, were conducted using the PeakForce Quantitative NanoMechanics (PF-QNM) mode at the nano scale. The average adhesion force between the tip and the target single TOCNF almost tripled after adsorption with Cu(II) from 50 pN to 140 pN. The stiffness of the TOCNF was also enhanced because the Cu(II) bound to the carboxylate groups and hardened the fiber. AFM topography, scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) mapping and X-ray photoelectron spectroscopy (XPS) indicated that the TOCNF were covered by copper nanolayers and/or nanoparticles after adsorption. The changes in the molecular structure caused by the adsorption were demonstrated by Raman and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). This methodology will be of great assistance to gain qualitative and quantitative information on the adsorption process and interaction between charged entities in aqueous medium.

  • 1860.
    Zhu, Mingzhao
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Lin, Shuangzheng
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zhao, Gui-Ling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Córdova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Organocatalytic diastereoselective dibromination of alkenes2010In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 51, no 20, p. 2708-2712Article in journal (Refereed)
    Abstract [en]

    A highly diastereoselective pyrrolidine-promoted dibromination of alkenes by combination of NBS and succinimide is presented. The pyrrolidine-mediated dibromination of alkenes is higly anti-selective and gives the corresponding products in moderate to high yields and up to >25:1 dr.

  • 1861.
    Zimmermann, Iwan
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    The Role of Tetrahedral Building Blocks in Low-Dimensional Oxohalide Materials2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The structural architecture found in low-dimensional materials can lead to a number of interesting physical properties including anisotropic conductivity, magnetic frustration and non-linear optical properties. There is no standard synthesis concept described thus far to apply when searching for new low-dimensional compounds, and therefore control on the design of the new materials is of great importance.This thesis describes the synthesis, crystal structure and characterization of some new transition metal oxohalide compounds containing p-elements having a stereochemically active lone-pair. First row transition metal cations have been used in combination with SeIV, SbIII and TeIV ions as lone-pair elements and Cl- and Br- as halide ions. The lone-pairs do not participate in covalent bonding and are responsible for an asymmetric one-sided coordination. Lone-pair elements in combination with halide ions have shown to be powerful structural spacers that can confine transition metal building blocks into low-dimensional arrangements. The halide ions and lone-pairs reside in non-bonded crystal volumes where they interact through weak van der Waals forces. The transition metal atoms are most often arranged to form sheets, chains or small clusters; most commonly layered compounds are formed.To further explore the chemical system and to separate the transition metal entities even more the possibility to include tetrahedral building blocks such as phosphate-, silicate-, sulphate- and vanadate building blocks into this class of compounds has been investigated. Tetrahedral building blocks are well known for their ability of segmenting structural arrangements by corner sharing, which often leads to the formation of open framework structures. The inclusion of tetrahedral building blocks led to the discovery of interesting structural features such as complex hydrogen bonding, formation of unusual solid solutions or faulted stacking of layers.Compounds for which phase pure material could be synthesized have been characterized in terms of their magnetic properties. Most compounds were found to have antiferromagnetic spin interactions and indications of magnetic frustration could be observed in some of them.

  • 1862.
    Zimmermann, Iwan
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Corgnet, Alexis
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Lidin, Sven
    Synthesis and crystal structure of a series of incommensurately modulated composite oxohalide compounds2014In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 43, no 42, p. 15812-15817Article in journal (Refereed)
    Abstract [en]

    Transparent, needle-like single crystals of the isostructural compounds [Sb4O7+3 delta X4][Zn-3](1+delta) = CL Br, I) delta approximate to 0.2 were obtained from chemical reactions in evacuated and sealed silica tubes. First, the average structure was solved in P211n but the model refined poorly and a lowering of the symmetry to the 3 + 1 dimensional space group P2(1)(alpha 0 gamma)0 gave a significantly better fit to the data. This model used second order positional modulations for all the atoms. Whereas Sb, Cl (Br, I) and most 0 positions were well behaved, there was a mismatch with Zn that was better described in a sub-cell, thus yielding a composite structure. The composite nature of the structure leads to a charge imbalance that is compensated by oxygen vacancies.

  • 1863.
    Zimmermann, Iwan
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    A Synthetic Route toward Layered Materials: Introducing Stereochemically Active Lone-Pairs into Transition Metal Oxohalides2014In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 14, no 10, p. 5252-5259Article in journal (Refereed)
    Abstract [en]

    The synthesis and crystal structure of eight new layered compounds in the (Mn2+, Fe2+)-(Sb3+, Te4+)-O-(Cl, Br) system are presented. Mn5Te4O12Cl2 (1), MnSb4O6Cl2 (2), Mn2Sb3O6Cl (3), Mn9Sb8O16Cl10 (4), Fe3Sb2O4Br4 (5), Fe7Sb10O18X8 [X = Cl (6), Br (7)], and Mn7Sb10O18Br8 (8). All of the compounds are made up of charge neutral layers held together through van der Waals interactions, except for compound 2, which has positively charged layers with halide ions between them that act as counterions. The transition metal atoms are confined in sheets within the layers and are thus well separated from each other along the stacking direction. The synthesis concept is based on utilizing both halide ions and p-elements having a stereochemically active lone pair that both act to open up crystal structures. This combination has proven to be a successful synthetic approach for finding new layered inorganic materials containing transition metals.

  • 1864.
    Zimmermann, Iwan
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Stacking faults in a layered cobalt tellurium phosphate oxochlorideManuscript (preprint) (Other academic)
  • 1865.
    Zimmermann, Iwan
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Stacking faults in a layered cobalt tellurium phosphate oxochloride2015In: Solid State Sciences, ISSN 1293-2558, E-ISSN 1873-3085, Vol. 40, p. 67-70Article in journal (Refereed)
    Abstract [en]

    The new compound Co2Te3(PO4)O6Cl was synthesized by chemical reactions in a sealed and evacuated silica tube. The crystal structure was solved from single crystal diffraction data and is made up by charge neutral layers. Within the layers two types of chains are made up by edge sharing [CoO6] and [CoO5Cl] polyhedra respectively. The chains are separated by tellurium oxide and phosphate building blocks. There are only weak Van der Waals interactions in between the layers and severe diffuse scattering is observed due to faulted stacking of the layers. Structure solutions in a P-1 triclinic cell and a larger monoclinic cell in P2(1)/c are discussed and compared to a computer generated model. The reasons for the stacking faults may be due to that there are two positions available for each layer that results in similar connectivity to the next layer in addition to the relatively wide channels in between the layers that reduce the Van der Waals interactions in between them.

  • 1866.
    Zimmermann, Iwan
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Synthesis and Crystal Structure of Mn3(Sb2O2)(VO4)2-x(SbO3)xCl2 (0.08<x<0.13), a vanadium oxochloride with a VV–SbIII split positionManuscript (preprint) (Other academic)
  • 1867.
    Zimmermann, Iwan
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Synthesis and Crystal Structure of the Iron(III) Oxotellurate(IV) Phosphate Oxide Chloride Fe11(TeO3)2(TeO4)3(PO4)2O4Cl32014In: Zeitschrift für Anorganische und Allgemeines Chemie, ISSN 0044-2313, E-ISSN 1521-3749, Vol. 640, no 12-13, p. 2435-2438Article in journal (Refereed)
    Abstract [en]

    The new compound Fe11(TeO3)2(TeO4)3(PO4)2O4Cl3 containing FeIII and TeIV crystallizes in the monoclinic space group C2/c with the unit cell parameters a = 20.5816(5) Å, b = 26.7506(6) Å, c = 5.03910(10) Å, β = 93.587(2)o, Z = 4. Single crystals were grown in sealed and evacuated silica tubes at 550 °C. The compound exhibits an open framework structure built from [FeO6], [FeO5Cl], [FeO4Cl], [PO4], [TeO3], and [TeO4] polyhedra. The TeIV atoms adopt a one sided asymmetric coordination due to the stereochemically active lone-pair. The lone-pairs together with the chloride ions are excluded from the covalently bonded space and protrude into cavities extending along [001]. Bond valence sum calculations confirm iron to be in its FeIII state and the chloride ions to be underbonded and act more as counterions than being fully integrated in the covalent network.

  • 1868.
    Zimmermann, Iwan
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Synthesis and Crystal Structure of the Solid Solution Co-3(SeO3)(3-x)(PO3OH)(x)(H2O) Involving Crystallographic Split Positions of Se4+ and P5+2013In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 52, no 20, p. 11792-11797Article in journal (Refereed)
    Abstract [en]

    Three new cobalt selenite hydroxo-phosphates laying in the solid solution Co-3(SeO3)(3-x)(PO3OH)(x)(H2O), with x = 0.8, x = 1.0, and x = 1.2 are reported. Single crystals were obtained by hydrothermal synthesis and the crystal structure was determined by single crystal X-ray diffraction. The structure can be described as a 3D framework having selenite and hydroxo-phosphate groups protruding into channels in the crystal structure. Se4+ and P5+ share a split position in the structure so that either SeO3 groups having a stereochemically active lone pair or tetrahedrally coordinated PO3OH groups are present. The OH-group is thus only present when the split position is occupied by P5+. The crystal water is coordinated to a cobalt atom and TG and IR measurements show that the water and hydroxyl groups leave the structure at unusually high temperatures (>450 degrees C). Magnetic susceptibility measurements show antiferromagnetic coupling below 16 K and a magnetic moment of 4.02(3) mu(B) per Co atom was observed.

  • 1869.
    Zimmermann, Iwan
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Lidin, Sven
    Crystalline Iron Oxohalide Nanotube Pea Pods2012In: European Journal of Inorganic Chemistry, ISSN 1434-1948, E-ISSN 1099-1948, no 25, p. 3971-3974Article in journal (Refereed)
    Abstract [en]

    Compounds Fe7Sb3(PO4)3O6Cl3 and Fe7Sb3(PO4)3O6Br3 are the first iron phosphates containing SbIII. They were synthesized by chemical vapor transport reactions, and their crystal structures were characterized by single-crystal X-ray diffraction. The compounds are isostructural and crystallize in the orthorhombic space group Pnma. Tubular Fe7(PO4)3O6X3 units (X = Cl, Br) are linked by SbO4 groups to build up a framework. The tubular units consist of an outer part made up of [FeO5X] octahedra where the Fe atoms are arranged to resemble a nanotube. Inside the tubes there are phosphate groups, and at the very center there is a chain of face-sharing [FeO6] octahedra.

  • 1870.
    Zimmermann, Iwan
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Kremer, Reinhard K.
    Hu, Shichao
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Synthesis, crystal structure and magnetic properties of a new copper oxo-antimony sulphate CuSb6O8(SO4)(2)2016In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 45, no 1, p. 392-396Article in journal (Refereed)
    Abstract [en]

    The new copper oxo-antimony sulphate CuSb6O8(SO4)(2) crystallizes in the triclinic space group P (1) over bar with the unit cell parameters a = 5.5342(4) angstrom, b = 7.6706(6) angstrom, c = 9.2374(7) angstrom, alpha = 96.505(5)degrees, beta = 93.818(4)degrees, gamma = 109.733(4)degrees and Z = 1. The crystal structure is made up of layers stacking along [001]. The layers are charge neutral and are connected to each other by only weak interactions. The copper atoms adopt a square planar [CuO4] coordination and such units are well separated from each other by corner and edge sharing to [SbO4] building blocks. The latter polymerize to form sheets with the formula [Sb3O8](infinity). Sulphate groups connect to the antimony oxide sheets by corner sharing and are located at the interface of the layers. Above similar to 10 K the magnetic susceptibility follows very well a Curie-Weiss law whereas below 10 K increasing deviations indicate the onset of antiferromagnetic correlations. Fitting the data in the range 10-50 K yields a Curie-Weiss temperature theta of -2.25(5) K. A sharp anomaly centered at T-C = 0.67 K in the heat capacity data indicates long-range magnetic ordering. Short range antiferromagnetic correlations well above T-C are seen in the magnetic contribution to the heat capacity and the magnetic susceptibility. These can be well described by the magnetism of a spin S = 1/2 Heisenberg chain with the nearest neighbor antiferromagnetic spin exchange interaction of J(intra) = similar to 2.8 K.

  • 1871.
    Zimmermann, Iwan
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Kremer, Reinhard K.
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Synthesis, crystal structure and magnetic properties of a new antimony sulphate oxide CuSb6(SO4)2O8Manuscript (preprint) (Other academic)
  • 1872.
    Zimmermann, Iwan
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Kremer, Reinhard K.
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Synthesis, crystal structure and magnetic properties of the open framework compound Co3Te2O2(PO4)2(OH)42011In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 184, no 11, p. 3080-3084Article in journal (Refereed)
    Abstract [en]

    The new compound Co(3)Te(2)O(2)(PO(4))(2)(OH)(4) was synthesized using hydrothermal techniques. It crystallizes in the monoclinic space group C2/m with the unit cell a=19.4317(10) angstrom, b=6.0249(3) angstrom, c=4.7788(2) angstrom, beta=103.139(5)degrees. The crystal structure is an open framework having chains of edge sharing [Co(1)O(6)] octahedra. Other building blocks are [TeO(3)(OH)(2)], [PO(4)] and [Co((2))O(2)(OH)(4)] connected mainly via corner sharing. The -OH groups protrude into channels in the structure. The magnetic susceptibility measured from 2 to 300 K shows two broad anomalies at around 21 K and 4 K. respectively. The peak at similar to 20 K is ascribed to a two-dimensional antiferromagnetic ordering of linear [Co(1)O(6)] chains coupled by interchain interaction via [PO(4)] groups in the Co(1) sheets. The second transition at 4 K is ascribed to a second antiferromagnetic ordering of the moments of the Co(2) entities via super-super exchange involving [PO(4)] and [TeO(3)(OH)(2)] groups. This assignment is strongly supported by low-temperature heat capacity measurements indicating an entropy removal within the high-temperature transition of about twice the magnitude of the low-temperature transition.

  • 1873.
    Zimmermann, Iwan
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Kremer, Reinhard K.
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Two isostructural layered oxohalide compounds containing Mn2+, Te4+ and Si4+; crystal structure and magnetic susceptibility2014In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 218, p. 6-9Article in journal (Refereed)
    Abstract [en]

    The new compounds Mn-4(TeO3)(SiO4)X-2 (X=Br, Cl) were synthesized by solid state reactions in sealed evacuated silica tubes. The compounds crystallize in the monoclinic space group P2(1)/m with the unit cell parameters a=5.5463(3) angstrom (5.49434(7) angstrom), b= 6.4893(4) angstrom (6.44184(9) angstrom), c=12.8709(7) A (12.60451 (18) angstrom), beta=93.559(5)degrees (94.1590(12)degrees) and Z=2 for the respective Br and Cl analogues. Manganese adopts various distorted coordination polyhedra; [MnO6] octahedra, [MnO5] tetragonal pyramids and [MnO2X2] tetrahedra. Other building blocks are [SiO4] tetrahedra and [TeO3] trigonal pyramids. The structure is made up from layers having no net charge that are connected via weak Van der Waal interactions. The layers that are parallel to (1 1 0) consist of two manganese oxide sheets which are separated by [Siad tetrahedra. On the outer sides of the sheets are the [MnO2X2] tetrahedra and the [TeO3] trigonal pyramids connected so that the halide ions and the stereochemically active lone pairs on the tellurium atoms protrude from the layers. Magnetic susceptibility measurements reveal a Curie law with a Weiss temperature of theta=-153(3) K for temperatures >= 100 K and indicate antiferromagnetic ordering at TN similar to 4 K. Possible structural origins of the large frustration parameter of f=38 are discussed.

  • 1874.
    Zimmermann, Iwan
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Kremer, Reinhard K.
    Reuvekamp, Patrick
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Crystal structure and magnetic properties of Cr3Te5O13Cl32013In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 42, no 24, p. 8815-8819Article in journal (Refereed)
    Abstract [en]

    A new chromium tellurite oxochloride, Cr3Te5O13Cl3, has been prepared by solid-state reaction and the crystal structure was determined by single crystal X-ray diffraction. The compound crystallizes in the non-centrosymmetric space group P2(1)2(1)2(1) with the unit cell a = 4.90180(10) angstrom, b = 17.3394(2) angstrom, c = 17.5405(2) angstrom, Z = 4, R-1 = 0.0282. The Cr3+ ions have octahedral [CrO6] oxygen coordination, the Te4+ ions have one sided [TeO3] and [TeO3Cl] coordinations. The [CrO6] octahedra are edge sharing and form chains extending along [100]. These are connected by corner sharing [TeO3] and [TeO3Cl] groups to form layers parallel to (110). The layers are connected by weak interactions in between Te4+ in the layers and Cl- ions located in between. The compound undergoes antiferromagnetic ordering at similar to 34 K with a Weiss constant of -230 K. Isothermal magnetization measurements reveal a critical field of about 0.25 T above which the magnetization versus field changes from linear to a Brillouin-like saturation behaviour. The frustration ratio amounts to similar to 6.8 indicative of sizable competing antiferromagnetic spin-exchange interaction. The dielectric constant epsilon (6 kHz) amounts to similar to 7.9 and decreases by about 1% on cooling from 50 K to liquid helium temperatures.

  • 1875. Zones, S. I.
    et al.
    Ruan, J.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Elomari, S.
    Terasaki, Osamu
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Chen, C. Y.
    Corma, A.
    Studies on zeolite SSZ-57: A structural enigma2011In: Solid State Sciences, ISSN 1293-2558, E-ISSN 1873-3085, Vol. 13, no 4, p. 706-713Article in journal (Refereed)
    Abstract [en]

    In this presentation we explore the characterization and catalytic behavior of zeolite SSZ-57. It has definite structural relationships to zeolite MEL, but then significant departures in the performance details. The HREM work carried out at the Terasaki lab attempts to develop a novel theory about this seeming contradiction in structural relation and performance divergence.

  • 1876. Zonouzi, Sajjad Ahangar
    et al.
    Khodabandeh, Rahmatollah
    Safarzadeh, Habibollah
    Aminfar, Habib
    Trushkina, Yuliya
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Mohammadpourfard, Mousa
    Ghanbarpour, Morteza
    Salazar Alvarez, German
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Experimental investigation of the flow and heat transfer of magnetic nanofluid in a vertical tube in the presence of magnetic quadrupole field2018In: Experimental Thermal and Fluid Science, ISSN 0894-1777, E-ISSN 1879-2286, Vol. 91, p. 155-165Article in journal (Refereed)
    Abstract [en]

    In this paper, the effects of applying magnetic field on hydrodynamics and heat transfer of Fe3O4/water magnetic nanofluid flowing inside a vertical tube have been studied experimentally. The applied magnetic field was resulted from quadrupole magnets located at different axial positions along the tube length. The variations of the local heat transfer coefficient and also the pressure drop of the ferrofluid flow along the length of the tube by applying the magnetic quadrupole field have been investigated for different Reynolds numbers. The obtained experimental results show maximum enhancements of 23.4%, 37.9% and 48.9% in the local heat transfer coefficient for the magnetic nanofluid with 2 vol% Fe3O4 in the presence of the quadrupole magnets located at three different axial installation positions for the Reynolds number of 580 and the relative increase in total pressure drop by applying the magnetic field is about 1% for Re = 580. The increase of the heat transfer coefficient is due to the radial magnetic force toward the heated wall generated by magnetic quadrupole field acting over the ferrofluid flowing inside the tube so that the velocity of the ferrofluid in the vicinity of the heated wall is increased. It is also observed that the enhancement of heat transfer coefficient by applying magnetic quadrupole is decreased with increasing the Reynolds number.

  • 1877.
    Zou, Ji
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Chinese Academy of Sciences, Shanghai.
    Liu, Jingjing
    Zhang, Guo-Jun
    Huang, Shuigen
    Vleugels, Jef
    Van der Biest, Omer
    Shen, Zhijian James
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hexagonal BN-encapsulated ZrB2 particle by nitride boronizing2014In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 72, p. 167-177Article in journal (Refereed)
    Abstract [en]

    A facile method based on an in situ reaction, called nitride boronizing, was first developed to directly coat ZrB2 particles with a nano-scale hexagonal boron nitride (h-BN) film. The crystallinity of the BN coating and the diameters of the ZrB2 particles could be tailored by changing the reaction conditions. A mechanism was proposed from thermodynamic calculations to clarify the formation of a core-shell nanostructure, i.e. the shock heat generated by the exothermal reaction. The core-shell ZrB2 powders showed excellent sinterability and the advantage in producing dense h-BN texture-free composites. Even when sintered at 2000 degrees C for 20 min and under a uniaxial pressure of 60 MPa, no texture created by h-BN was observed. The isotropic bending strength (similar to 300 MPa) of ZrB2-37 vol.% BN ceramics from core-shell precursor powders were investigated and compared with ceramics of the same nominal composition, but densified from commercial powders containing highly aligned h-BN grains. The nitride boronizing approach could be explored to synthesize other h-BN-coated IVB group transition metal borides.

  • 1878.
    Zou, Ji
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Shanghai Institute of Ceramics, China; KU Leuven, Belgium.
    Liu, Jingjing
    Zhao, Jian
    Zhang, Guo-Jun
    Huang, Shuigen
    Qian, Bin
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Vleugels, Jef
    Van der Biest, Omer
    Shen, James Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    A top-down approach to densify ZrB2-SiC-BN composites with deeper homogeneity and improved reliability2014In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 249, p. 93-101Article in journal (Refereed)
    Abstract [en]

    A novel top down approach was developed to fabricate dense ZrB2-SiC-BN (ZSN) composites with a fine-grained (<1 mu m) microstructure using coarse-grained (similar to 10 mu m) ZrN and Si precursors that reacted with fine (similar to 0.5 mu m) B4C powders at 1850 degrees C. The results show that the reaction and densification mechanisms acting during sintering could be separated or happen simultaneously by changing the pressure loading strategy. Loading cycles not only have a substantial influence on the microstructure homogeneity and the strength reliability of as sintered composites, but might alter the electric current path during the Spark Plasma Sintering process as well. A residual compressive stress of 361 MPa, generated upon the SiC grains in the ZSN composites, was measured by Raman spectroscopy. The fine SiC grains tended to form larger clusters in the dense microstructure if the loading cycle is inappropriate, which was further employed to interpret the observed scattering of strength values in one batch of ZSN. The 48ZrB(2)-24SiC-28BN (number in vol%) composite has an average strength of 473 MPa, which was 94% of that of in situ densified ZrB2-SiC ceramics (ZS). Considering the corresponding Youngs modulus was only half of that for ZS, the in situ ZSN composite owns a better mechanical strain tolerance.

  • 1879. Zou, Ji
    et al.
    Zhang, Guo-Jun
    Shen, Zhi-Jian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Tsinghua University, China.
    Binner, Jon
    Ultra-low temperature reactive spark plasma sintering of ZrB2-hBN ceramics2016In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 36, no 15, p. 3637-3645Article in journal (Refereed)
    Abstract [en]

    Starting from ZrN and amorphous boron, dense ZrB2 ceramics with 37 vol% hexagonal BN were consolidated by spark plasma sintering. Benefiting from the moderate exothermic reaction between ZrN and B and the resultant fine powder generated, ZrB2-BN ceramics with relative density of 94% could be reached at 1100 degrees C, further improved to 97% by 1550 degrees C. The effects of sintering temperature and holding time on the densification behavior, microstructural evolution and mechanical properties of ZrB2-BN ceramics were investigated. ZrB2-37 vol%BN ceramics densified at 1700 degrees C exhibited attractive mechanical performance: a three-point bending strength of 353 MPa, a Vicker's hardness of 6.7 GPa and a Young's modulus of 197.5 GPa. Note that its strength dropped sharply to 191 MPa measured at 1300 degrees C. The combination of low sintering temperature (1100-1550 degrees C), low Young's modulus (180-200 GPa) and relatively high strength (200-350 MPa) make reactively sintered ZrB2-BN composites as promising matrix for continuous fiber reinforced composites.

  • 1880.
    Zou, Ji
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zhong, Yuan
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Eriksson, Mirva
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Liu, Leifeng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Tougher zirconia nanoceramics with less yttria2019In: Advances in Applied Ceramics: Structural, Functional and Bioceramics, ISSN 1743-6753, E-ISSN 1743-6761, Vol. 118, no 1-2, p. 9-15Article in journal (Refereed)
    Abstract [en]

    Reducing the grain size in zirconia ceramics has shown to decrease its toughness by size-dependent stabilisation of the tetragonal phase that, in turn, hinders the stress-induced phase transformation from tetragonal to monoclinic. The stability of the tetragonal phase increases with the decrease of grain size but decreases with the reduction of the amount of yttria added, implying the need for adjustment of the yttria content when a nano-grained structure is of concern. In this study, low-yttria compositions were investigated. The ceramics were prepared with two sintering methods namely spark plasma sintering (SPS) and pressureless sintering. A clear tendency was noted for the indentation toughness increase with the reduction of yttria content, and a higher toughness achieved in as-SPSed samples in comparison with the annealed samples. The origins of the increased toughness were discussed in terms of yttria content, carbon contamination and increased oxygen vacancies after sintering at reducing atmosphere in SPS.

  • 1881.
    Zou, Ji
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zhong, Yuan
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zhang, Jun-Zhan
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Xi'an University of Architecture & Technology, China.
    Ekelund, Magnus
    Shen, Zhi-Jian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Separating macrostresses from microstresses in Al2O3-15 vol%SiC particulate reinforced composites2015In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 109, p. 84-88Article in journal (Refereed)
    Abstract [en]

    Macrostresses and microstresses coexist in ceramics, but are difficult to distinguish. In this work, these two types of residual stresses were separated by comparing the stress levels on the mechanically and argon beam polished surfaces of Al2O3-15 vol%SiC particulate reinforced composites. Stresses were measured using the shift of a Raman peak of beta-sic, the shift of a luminescence line of alpha-Al2O3 and a self-consistent approach. The critical grain size of SiC, over which will result in the crack formation in Al2O3 matrix, was calculated to be 13.5-26.4 mu m. New microcracldng did not form in Al2O3 grains during progressive mechanical polishing.

  • 1882.
    Zou, Xiaodong
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Hovmöller, Sven
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Quantitative 3D electron microscopy and 3D electron diffraction2010In: Journal of Chinese Electron Microscopy Society, Vol. 29, p. 230-243Article in journal (Refereed)
    Abstract [en]

    Electron crystallography can be used for determination of atomic structures of micrometer-/ nanometer-sized crystals, which are million times smaller than those required by X-ray crystallography. Structure determination at atomic resolution can be done from both high-resolution electron microscopy images combined with crystallographic image processing and electron diffraction data, or by combining them with powder X-ray diffraction data. Atoms may be overlapped in all projections if the unit cell of the crystal is large. In such cases, atomic structures can be obtained by collecting several diffraction patterns and images from different directions and combining them to reconstruct a three-dimensional potential map. In this paper, some recent developments of electron crystallography and its applications in structure determination of inorganic crystals in the past decade are shown.

     

  • 1883.
    Zou, Xiaodong
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Yao, Qingxia
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bermejo Gómez, Antonio
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Su, Jie
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Pascanu, Vlad
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Yifeng, Yun
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zheng, Haoquan
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Chen, Hong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Liu, Leifeng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Abdelhamid, Hani N.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Martín-Matute, Belén
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    A series of highly stable isoreticular lanthanide metal-organic frameworks with tunable luminescence properties solved by rotation electron diffraction and X-ray diffraction2016In: Acta Crystallographica Section A: Foundations of Crystallography, ISSN 0108-7673, E-ISSN 1600-5724, Vol. A72, p. 136-136Article in journal (Refereed)
  • 1884. Zubkov, V G
    et al.
    Pereliaev, V A
    Institute of Solid State Chemistry, Russian Academy of Science, Ekaterinburg, Russia.
    Tyutyunnik, A P
    Institute of Solid State Chemistry, Russian Academy of Science, Ekaterinburg, Russia.
    Kohler, J
    Max Planck Institute - Solid State Chemistr, Stuttgart, Germany.
    Simon, A
    Max Planck Institute - Solid State Chemistr, Stuttgart, Germany.
    Svensson, Gunnar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Condensed cluster phases in reduced oxoniobates: synthesis and studies of Sr4−xNb17O26 (x=0.0(1), 0.3(1)) and Eu4−xNb17O26 (x=0.3(1)):  1997In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 256, p. 129-139Article in journal (Refereed)
    Abstract [en]

    Sr4−xNb17O26 (x=0.0, 0.3) and Eu4−xNb17O26 (x = 0.3) were synthesised from SrCO3/Eu2O3 and Nb2O5 in a vacuum furnace at temperatures up to 1600°C (1500°C for Eu) using acetylene soot or Nb as reducing agents. The synthetic studies show that these phases are only formed via an intermediate disordered ‘phase’ (or phasoid). Sr4−xNb17O26 and Eu4−xNb17O26 are isostructural with Ba4Nb17O26 and crystallise in space group P 4/m (83) with the unit cell parameters for   and and , respectively. The crystal structure can be described as an intergrowth between ANbO3 and NbO. Characteristic building blocks are quadruple chains of corner-sharing Nb6-octahedra. ?The structures of Sr4−xNb17O26 and Eu4−xNb17O26 were refined using X-ray powder diffraction and neutron diffraction data (only Sr4−xNb17O26). The Rietveld refiniments and microanalyses showed x in Eu4−xNb17O26 to be 0.3(l) while the Sr analogue both x= 0.0(1) and 0.3(1) were found. High resolution electron microscopy studies showed that the compounds frequently contained structural defects. The magnetic susceptibility of Eu4−xNb17O26 (x=0.3) shows a Curie-Weiss behaviour, with a magnetic moment in good agreement with the expected μeff=7.9 μB for Eu2+/ The Sr analogie is temperature-independent paramagnetic at room temperature, Sr4−xNb17O26 (x=0.3) and Eu4−xNb17O26 (x=0.3) are metallic, with a resistivity increasing with temperature.

  • 1885. Zubkov, V. G.
    et al.
    Surat, L. L.
    Tyutyunnik, A. P.
    Berger, I. F.
    Tarakina, N. V.
    Slobodin, B. V.
    Kuznetsov, M. V.
    Denisova, T. A.
    Zhuravlev, N. A.
    Perelyaeva, L. A.
    Baklanova, I. V.
    Shein, I. R.
    Ivanovskii, A. L.
    Shulgin, B. V.
    Ishchenko, A. V.
    Tcherepanov, A. N.
    Svensson, Gunnar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Forslund, Bertil
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Skripkin, M. Yu.
    Structural, vibrational, electronic, and luminescence properties of the cyclotetravanadates A(2)M(VO3)(4) (A=Na,Ag; M=Ca,Sr)2008In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 77, no 17, p. 174113-Article in journal (Refereed)
    Abstract [en]

    The physical properties of the family of cyclotetravanadates A(2)M(VO3)(4), where A=Na,Ag and M=Ca,Sr, have been studied by means of x-ray powder diffraction, neutron diffraction, electron diffraction, infrared, Raman, NMR, photoexcitation and pulse cathode beam excitation, and x-ray photoelectron spectroscopies, and band structure calculations. The differences between the structural, vibrational, luminescence, and electronic properties of the alkali metal-containing [Na2Ca(VO3)(4) and Na2Sr(VO3)(4)] and the d metal-containing cyclotetravanadates [Ag2Ca(VO3)(4) and Ag2Sr(VO3)(4)] are analyzed. Na2Ca(VO3)(4), Ag2Ca(VO3)(4), Na2Sr(VO3)(4), and Ag2Sr(VO3)(4) have tetragonal structures, P4/nbm, with a=10.438 49(6), 10.445 24(5), 10.634 49(4), and 10.625 74(6), and c=4.938 73(5), 4.968 45(5), 4.962 05(4), and 4.979 30(4) angstrom, respectively. The main structural feature of A(2)M(VO3)(4) is the tetracyclic [V4O12] units. The hybridized O 2p-V 3d states of the tetracyclic [V4O12] units have a dominant influence on the electronic structure of these compounds. The compounds are semiconducting with a local density approximation band gap increasing, from 1.85 eV for Ag2Ca(VO3)(4) to 3.02 eV for Na2Ca(VO3)(4). The prospects of these compounds as advanced materials for detectors of photon and corpuscular radiation as well as for color correction of light emission sources such as lamp and light emitting diode sources are discussed.

  • 1886. ZUBKOV, VG
    et al.
    PERELEYAEV, VA
    TYUTYUNNIK, AP
    KONTSEVAYA, IA
    VORONIN, VI
    SVENSSON, G
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    SYNTHESIS, HIGH-RESOLUTION ELECTRON-MICROSCOPY AND CRYSTAL-STRUCTURE REFINEMENT OF THE CLUSTER COMPOUND BA3NB16O23 BY X-RAY AND NEUTRON-DIFFRACTION1994In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 203, p. 209-216Article in journal (Refereed)
    Abstract [en]

    Ba3Nb16O23 was prepared by reducing a mixture of BaCO3 and Nb2O5 with acetylene soot under vacuum at 1550-1600-degrees-C. The structure was determined from high resolution electron microscopy images and was refined by the Rietveld technique using X-ray and neutron powder diffraction data. The unit cell parameters are a = 20.9301(4) angstrom, b = 12.4785(3) angstrom and c = 4.1619(1) angstrom, space group Cmmm, Z = 2. The crystal structure can be described as an intergrowth of BaNbO3 and NbO. Characteristic building units are quadruple chains of corner-sharing Nb6 octahedra connected via columns with a perovskite-type structure to form a three-dimensional network.

  • 1887. ZUBKOV, VG
    et al.
    TYUTYUNNIK, AP
    PERELIAEV, VA
    SHVEIKIN, GP
    KOHLER, J
    KREMER, RK
    SIMON, A
    Svensson, Gunnar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Synthesis and Structural, Magnetic and Electrical Characterization of the Reduced Oxoniobates BaNb8O14, EuNb8O14, Eu2Nb5O9 and EuxNbO3 (x = 0.7, 1.0).1995In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 226, p. 24-30Article in journal (Refereed)
    Abstract [en]

    Powder samples of the reduced oxoniobates Eu0.7NbO3, EuNbO3, Eu2Nb5O9, EuNb8O14 and BaNb8O14 have been synthesised. EuNbO3 and Eu0.7NbO3 adopt the perovskite type structure (space group Pm3m) with unit cell parameters a = 4.021 (1) and 3.981 (3) Angstrom, respectively. Eu,Nb,Og exhibits an intergrowth structure which can be described as alternating slabs of NbO and EuNbO3. It crystallises in P4/mmm with a = 4.131(1) and c = 12.043(5) Angstrom. EuNb8O14 and the here synthesised modification of BaNb8O14 is isostructural with SrNb8O14. The structures of EuNb8O14 and BaNb8O14 have been refined from X-ray powder diffraction data with the Rietveld technique, They have the unit cell parameters a = 9.2272(1), b = 10.2647(2), c = 5.9381(1) and a = 9.3451(1), b = 10.2689(2), c = 5.9470(4) Angstrom, (space group Pbam), respectively. In all the studied compounds AO(12) cuboctahedra (A = Eu, Ba) form either chains (in ANb(8)O(14)), double layers (in Eu2Nb5O9) or three-dimensional nets (in EuNbO3 and Eu0.7NbO3). Magnetic susceptibility measurements show temperature independent paramagnetism for BaNb8O14, while the susceptibilities of the Eu niobates follow Curie-Weiss laws with effective magnetic moments in good agreement with the expected mu(eff)=7.9 mu(B) for EU(2+). Eu0.7NbO3 and Eu1.0NbO3 exhibit ferromagnetic ordering below 4 K. BaNb8O14 and EuNb8O14 are semiconductors, while Eu2Nb5O9, EuNbO3 and Eu0.7NbO3 are metallic.

  • 1888.
    Åkerblom, Ida E.
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Ojwang, Dickson O.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Grins, Jekabs
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Svensson, Gunnar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    A thermogravimetric study of thermal dehydration of copper hexacyanoferrate by means of model-free kinetic analysis2017In: Journal of thermal analysis and calorimetry (Print), ISSN 1388-6150, E-ISSN 1588-2926, Vol. 129, no 2, p. 721-731Article in journal (Refereed)
    Abstract [en]

    The kinetics of thermal dehydration of K2x/3Cu[Fe(CN)6]2/3·nH2O was studied using thermogravimetry for x = 0.0 and 1.0. Data from both non-isothermal and isothermal measurements was used for model-free kinetic analysis by the Friedman and KAS methods. The water content was determined to be n = 2.9 – 3.9, with an additional ~10% of water, likely surface adsorbed, that leaves very fast when samples are exposed to a dry atmosphere. The determined activation energies are 19 kJ (mol H2O)-1 for x = 0.0 and 16 kJ (mol H2O)-1 for x = 1.0. The dehydration is adequately described as a diffusion controlled single step reaction following the D3 Jander model. The determined dehydration enthalpy is, 11 kJ (mol H2O)-1 for x = 0.0 and 27 kJ (mol H2O)-1 for x = 1.0, relative to that of water. The increase with increasing x is evidence for that the H2O molecules form bonds to the incorporated K+ ions.

  • 1889.
    Ångström, Jonas
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Chen, Hong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Accurate lattice-parameter determination from electron diffraction tomography data using two-dimensional diffraction vectors2018In: Journal of applied crystallography, ISSN 0021-8898, E-ISSN 1600-5767, Vol. 51, p. 982-989Article in journal (Refereed)
    Abstract [en]

    Electron diffraction tomography (EDT) has emerged as a successful tool for ab initio atomic structure determination of nanometre-sized crystals. However, lattice parameters obtained from EDT data are often of lower accuracy than those from powder X-ray data, owing to experimental errors and data-processing methods. This work describes a lattice-parameter refinement method for EDT data using two-dimensional diffraction vectors and shows that the accuracy of lattice-parameter determination can be improved significantly. It is also shown that the method is tolerant to sample displacement during data collection and to geometric distortions in the electron diffraction patterns due to lens imperfections. For the data sets tested, the method reduces the 95% confidence interval of the worst errors in angles from +/- 1.98 to +/- 0.82 degrees and the worst relative errors of the unit-cell lengths from +/- 1.8% to +/- 1.3%, compared with the conventional method using clustering of three-dimensional diffraction vectors. The improvement is attributed to the fact that the new method makes use of the positions of two-dimensional diffraction spots, which can be determined with high accuracy, and disregards the position of the central beam, the orientation of the rotation axis and the angles of the diffraction frames, whose errors all contribute to the errors for lattice-parameter determination using the three-dimensional method.

  • 1890.
    Ångström, Jonas
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Jenei, István Zoltán
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Spektor, Kristina
    Häussermann, Ulrich
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Formation of Hydrous, Pyroxene-Related Phases from LiAlSiO4 Glass in High-Pressure Hydrothermal Environments2019In: ACS Earth and Space Chemistry, ISSN 2472-3452, Vol. 3, no 1, p. 8-16Article in journal (Refereed)
    Abstract [en]

    Hydrous Al-bearing pyroxene-related phases were synthesized by subjecting LiAlSiO4 glass to hydrothermal environments at pressures of 5-10 GPa and temperatures of 400-600 degrees C. LiAlSiO3(OH)(2) formed at 5 GPa, whereas at 10 GPa, product mixtures of LiAlSiO3(OH)(2) and Li3Al4(Si2O7)(SiO3)(2)(OH)(5) were obtained. The monoclinic structure of LiAlSiO3(OH)(2) has been previously characterized from single-crystal X-ray diffraction data (Spektor, K.; Fischer, A.; Haussermann, U. Crystallization of LiAlSiO4 Glass in Hydrothermal Environments at Gigapascal Pressures-Dense Hydrous Aluminosilicates. Inorg. Chem. 2016, 55 (16), 8048-8058, 10.1021/acs.inorgchem.6b01181). It resembles that of alpha-spodumene (LiAlSi2O6) and constitutes alternating layers of chains of corner-condensed SiO4 tetrahedra and chains of edge-sharing AlO6 octahedra. OH groups are part of the octahedral Al coordination and extend into channels provided within the SiO4 tetrahedron chain layers. The structure solution of Li3Al4(Si2O7)(SiO3)(2)(OH)(5), as detailed here, was achieved by rotational electron diffraction analysis, and the model was refined against synchrotron powder X-ray diffraction data (space group C2/c, a = 4.921 angstrom, b = 25.849 angstrom, c = 9.170 angstrom, and beta = 99.42 degrees). The crystal structure of Li3Al4(Si2O7)(SiO3)(2)(OH)(5) features chains and pairs of corner-condensed SiO4 tetrahedra, with the Si atoms equally distributed among the two structural units, and thus Li3Al4(Si2O7)(SiO3)(2)(OH)(5) is a rare example of a mixed inosorosilicate. LiAlSiO3(OH)(2) and Li3Al4(Si2O7)(SiO3)(2)(OH)(5) are structurally closely related to recently discovered hydrous magnesium aluminosilicate phases (i.e., HAPY and HySo), which form at conditions similar to the hydrous lithium aluminosilicates. The conjecture is made that hydrothermal environments following chlorite but also lawsonite breakdown generally afford conditions for the formation of hydrous, pyroxene-related, aluminosilicate phases, with compositions of M2(1-m)M1TO(3+n)(OH)(2-o) (0 < m, n, and o < 1). These phases could be transients in breakdown reactions but also stable at cold slab conditions and, thus, may play an important role to water storage and transport to the transition zone.

  • 1891. Ångström, Jonas
    et al.
    Johansson, Robert
    Sarkar, Tapati
    Sörby, Magnus H.
    Zlotea, Claudia
    Andersson, Mikael S.
    Nordblad, Per
    Scheicher, Ralph H.
    Häussermann, Ulrich
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Sahlberg, Martin
    Hydrogenation-Induced Structure and Property Changes in the Rare-Earth Metal Gallide NdGa: Evolution of a [GaH](2-) Polyanion Containing Peierls-like Ga-H Chains2016In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 55, no 1, p. 345-352Article in journal (Refereed)
    Abstract [en]

    The hydride NdGaH1+x (x approximate to 0.66) and its deuterized analogue were obtained by sintering the Zintl phase NdGa with the CrB structure in a hydrogen atmosphere at pressures of 10-20 bar and temperatures near 300 degrees C. The system NdGa/NdGaH1+x exhibits reversible H storage capability. H uptake and release were investigated by kinetic absorption measurements and thermal desorption mass spectroscopy, which showed a maximum H concentration corresponding to NdGaH2 (0.93 wt % H) and a two-step desorption process, respectively. The crystal structure of NdGaH1+x was characterized by neutron diffraction (P2(1)/m, a = 4.1103(7), b = 4.1662(7), c = 6.464(1) angstrom, beta = 108.61(1)degrees Z = 2). H incorporates in NdGa by occupying two distinct positions, H1 and H2. HI is coordinated in a tetrahedral fashion by Nd atoms. The H2 position displays flexible occupancy, and H2 atoms attain a trigonal bipyramidal coordination by centering a triangle of Nd atoms and bridging two Ga atoms. The phase stability and electronic structure of NdGaH1+x, were analyzed by first-principles DFT calculations. NdGaH1H2 (NdGaH2) may be expressed as Nd3+(H1(-)[GaH2](2-). The two-dimensional polyanion [GaH](2-) features linear -H-Ga-H-Ga- chains with alternating short (1.8 A) and long (2.4 angstrom) Ga-H distances, which resembles a Peierls distortion. H2 deficiency (x < 1) results in the fragmentation of chains. For x = 0.66 arrangements with five-atom moieties, Ga-H-Ga-H-Ga are energetically most favorable. From magnetic measurements, the Curie-Weiss constant and effective magnetic moment of NdGaH1.66 were obtained. The former indicates antiferromagnetic interactions, and the latter attains a value of similar to 3.6 mu(B), which is typical for compounds containing Nd3 ions.

  • 1892. Österberg, Carin
    et al.
    Fahlquist, Henrik
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Häussermann, Ulrich
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Brown, Craig M.
    Udovic, Terrence J.
    Karlsson, Maths
    Dynamics of Pyramidal SiH3- Ions in ASiH(3) (A = K and Rb) Investigated with Quasielastic Neutron Scattering2016In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, no 12, p. 6369-6376Article in journal (Refereed)
    Abstract [en]

    The two alkali silanides ASiH(3) (A = K and Rb) were investigated by means of quasielastic neutron scattering, both below and above the order-disorder phase transition occurring at around 275-300 K. Measurements upon heating show that there is a large change in the dynamics on going through the phase transition, whereas measurements upon cooling reveal a strong hysteresis due to undercooling of the disordered phase. The results show that the dynamics is associated with rotational diffusion of SiH3- anions, adequately modeled by H-jumps among 24 different jump locations radially distributed around the Si atom. The average relaxation time between successive jumps is of the order of subpicoseconds and exhibits a weak temperature dependence with a small difference in activation energy between the two materials, 39(1) meV for KSiH3 and 33(1) meV for RbSiH3. The pronounced SiH3- dynamics explains the high entropy observed in the disordered phase resulting in the low entropy variation for hydrogen absorption/desorption and hence the origin of these materials' favorable hydrogen storage properties.

  • 1893.
    Šoltésová, Mária
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Charles University in Prague, Department of low temperature physics.
    Fast Dynamic Processes in Solution Studied by NMR Spectroscopy2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Nuclear magnetic resonance (NMR) spectroscopy is capable to deliver a detailed information about the dynamics on molecular level in a wide range of time scales, especially if accompanied by suitably chosen theoretical tools. In this work, we employed a set of high-resolution NMR techniques to investigate dynamics processes in several weakly interacting molecular systems in solution.

    Van der Waals interactions play an important role in inclusion complexes of cryptophane-C with chloroform or dichloromethane. The complex formation was thoroughly investigated by means of 1H and 13C NMR experiments along with the quantum-chemical density functional theory (DFT) calculations. We characterized kinetics, thermodynamics, as well as fine details of structural rearrangements of the complex formation.

    Internal dynamics of oligo- and polysaccharides presents a considerable challenge due to possible coupling of internal and global molecular motions. Two small oligosaccharides were investigated as test cases for a newly developed integrated approach for interpreting the dynamics of the molecules with non-trivial internal flexibility. The approach comprised advanced theoretical tools, including stochastic modeling, molecular dynamics (MD) simulations, and hydrodynamic simulations.

    A biologically important bacterial O-antigenic polysaccharide from E. Coli O91 was addressed employing selective isotope labeling and multiple-field 13C relaxation experiments. The complex dynamics of the polysaccharide is characterized by the conformational motion of the exocyclic groups of the sugars, superimposed to the breathing motion of the polymeric chain.

    Hydrogen bonding is another major non-covalent interaction. Dilute solutions of ethanol were chosen as a model of liquid systems containing extensive hydrogen-bonded networks. We developed a new methodology consisting of NMR diffusion measurements, DFT calculations, and hydrodynamic modeling and utilized it to determine average size of the molecular clusters of ethanol at given conditions.

  • 1894.
    Šoltésová, Mária
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Charles University in Prague.
    Kowalewski, Jozef
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Dynamics of exocyclic groups in the Escherichia coli O91 O-antigen polysaccharide in solution studied by carbon-13 NMR relaxation2013In: Journal of Biomolecular NMR, ISSN 0925-2738, E-ISSN 1573-5001, Vol. 57, no 1, p. 37-45Article in journal (Refereed)
    Abstract [en]

    Carbon-13 relaxation data are reported for exocyclic groups of hexopyranosyl sugar residues in the repeating unit within the Escherichia coli O91 O-antigen polysaccharide in a dilute D2O solution. The measurements of T 1, T 2 and heteronuclear nuclear Overhauser enhancements were carried out at 310 K at two magnetic fields (16.4 T, 21.1 T). The data were analyzed using the standard and extended Lipari–Szabo models, as well as a conformational jump model. The extended version of the Lipari–Szabo and the two-site jump models were most successful for the hydroxymethyl groups of Gal and GlcNAc sugar residues. Different dynamics was found for the hydroxymethyl groups associated with different configurations (d-gluco, d-galacto) of the sugar residues, the latter being faster than the former.

  • 1895.
    Šoltésová, Mária
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Charles University in Prague.
    Peksa, Mikuláš
    Benda, Ladislav
    Czernek, Jiří
    Lang, Jan
    Determination of size of molecular clusters of ethanol by means of diffusion NMR and hydrodynamic calculationsManuscript (preprint) (Other academic)
    Abstract [en]

    Microscopic structure of ethanol in liquid state is characterized as dynamic equilibrium of hydrogen bonded clusters of different sizes and topologies. We have developed a novel method for determination of average size of the clusters that combines measurement of diffusion coefficient by means of PFG NMR technique and hydrodynamic simulations. The approach includes the use of HydroNMR [de la Torre 2000] for small molecules, which is attained here by the calibration procedure using dilute solution of tetramethylsilane. It is thus possible to correlate the experimentally determined apparent hydrodynamic radius of ethanol with calculated hydrodynamic radii of the modeled clusters of different sizes. We found that average size of the clusters in 0.16 M solution of ethanol in hexane ranges from monomer above 300 K to hexamer below 200 K. The clusters in the case of 0.44 M are generally slightly larger – from average size of dimer at 320 K to heptamer below 210 K.

35363738 1851 - 1895 of 1895
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