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  • 1. Banenzoue, Charles
    et al.
    Ponou, Simeon
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    Lambi, John Ngolui
    Non-isovalent substitution in a Zintl phase with the TiNiSi type structure, CaMg1-xAgxGe [x=0.13 (3)]2009In: Acta Crystallographica Section E: Structure Reports Online, ISSN 1600-5368, E-ISSN 1600-5368, Vol. 65, p. i90-U56Article in journal (Refereed)
    Abstract [en]

    Single crystals of the title Ag-substituted calcium magnesium germanide, CaMg1-xAgxGe [x = 0.13 (3)] were obtained from the reaction of the corresponding elements at high temperature. The compound crystallizes with the TiNiSi structure type (Pearson code oP12) and represents an Ag-substituted derivative of the Zintl phase CaMgGe in which a small fraction of the divalent Mg atoms have been replaced by monovalent Ag atoms. All three atoms in the asymmetric unit (Ca, Mg/Ag, Ge) occupy special positions with the same site symmetry (.m.). Although the end member CaAgGe has been reported in an isomorphic superstructure of the same TiNiSi type, higher Ag content in solid solutions could not be achieved due to competitive formation of other, perhaps more stable, phases.

  • 2.
    Bryntse, Ingrid
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    Studies of systems related to high-Tc superconductors by electron microscopy and X-ray powder diffraction1992Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    New cuprate systems related to high temperature superconductors have been investigated and are reviewed. The synthesized samples have been studied mainly by transmission electron microscopy, energy-dispersive spectrometry and X-ray powder diffraction, in order to determine composition and structure of the formed phases.

    The following compounds were studied: Bi14Cu10Nb16O7 and Bit 7Cuo.2Ti2.006.8, both of cubic pyrochlore-type structure; BiNbs.4015, a tetragonal tungsten bronze type compound; Bi2/3Cu3Ti4012, a perovskite-related phase; Ba4CuYW2012, with a perovskite based unit cell; LaSrCuGaOs and LaCaCuGaOs, both of brownmillerite type and some related phases obtained by aliovalent substitution; R2Hg04 (R = La, Nd, Sm, Eu and Gd), with a new type of structure; and HgBa^RCugOy (R = La, Nd, Eu, Eu+Ca, Gd, Dy and Y), new "Hg-1212" type phases with a structure related to that of the thallium superconductor TlBa2CaCu207.

    The structural features of these compounds of relevance to superconductivity are also discussed.

  • 3. Chaim, Rachman
    et al.
    Kalina, Michael
    Shen, James Z.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    Transparent yttrium aluminum garnet (YAG) ceramics by spark plasma sintering2007In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 27, no 11, p. 3331-3337Article in journal (Refereed)
    Abstract [en]

    Commercial nanocrystalline yttrium aluminum garnet (nc-YAG) powders were used for fabrication of dense and transparent YAG by spark plasma sintering (SPS). Spherical 34 nm size particles were densified by SPS between 1200 and 1500 degrees C using 50 and 100 MPa pressures for 3, 6, and 9 min durations. Fully dense and transparent polycrystalline cubic YAG with micrometer grain size were fabricated at very moderate SPS conditions, i.e. 1375 degrees C, 100 MPa for 3 min. Increase in the SPS duration and pressure significantly increased the density especially at the lower temperature range. The observed microstructure is in agreement with densification by nano-grain rotation and sliding at lower densities, followed by curvature driven grain boundary migration and normal grain growth at higher densities. Residual nanosize pores at the grain boundary junctions are an inherent microstructure feature due to the SPS process.

  • 4. Dahl, P.
    et al.
    Kaus, I.
    Zhao, Z.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    Nygren, M.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    Wiik, K.
    Grande, T.
    Einarsrud, M. -A
    Densification and properties of zirconia prepared by three different sintering techniques2007In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 33, no 8, p. 1603-1610Article in journal (Refereed)
    Abstract [en]

    Densification of nanocrystalline yttria stabilized zirconia (YSZ) powder with 8 mol% Y2O3, prepared by a glycine/nitrate smoldering combustion method, was investigated by spark plasma sintering, hot pressing and conventional sintering. The spark plasma sintering technique was shown to be superior to the other methods giving dense materials (>= 96%) with uniform morphology at lower temperatures and shorter sintering time. The grain size of the materials was 0.21, 0.37 and 12 mu m after spark plasma sintering, hot pressing and conventional sintering, respectively. Total electrical conductivity of the materials showed no clear correlation with the grain size, but the activation energy for spark plasma sintered materials was slightly higher than for materials prepared by the two other densification methods. The hardness, measured by the Vickers indentation method, was found to be independent on grain size while fracture toughness, derived by the indentation method, was slightly decreasing with increasing grain size.

  • 5. Dominguez-Rodriguez, Arturo
    et al.
    Gomez-Garcia, Diego
    Zapata-Solvas, Eugenio
    Shen, James Z.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    Chaim, Rachman
    Making ceramics ductile at low homologous temperatures2007In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 56, no 2, p. 89-91Article in journal (Refereed)
    Abstract [en]

    Polycrystalline ceramics are brittle at room temperature but may deform by dislocation slip processes at higher temperatures, where T >= 0.5 T-M (T-M, the melting temperature), leading to strain hardening, i.e. the total strain to rupture is limited. We show that mutual sliding of nanometer grains and atomic transport along their boundaries enables low-temperature metal-like plasticity in nanocrystalline ceramics. Compression of fully dense MgO nanoceramics at temperatures as low as 700 degrees C (0.31 T-M) exhibited stress-strain curves with no strain hardening.

  • 6.
    Eden, Mattias
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Physical Chemistry.
    Grins, Jekabs
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    Jansson, Kjell
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Materials Chemistry.
    Al and O substitutions in BaS-phases, Ba2AlxSi12-xN16-xO2+x: A TEM, XRD and solid-state NMR study2008In: Solid State Sciences, ISSN 1293-2558, E-ISSN 1873-3085, Vol. 10, no 1, p. 50-60Article in journal (Refereed)
    Abstract [en]

    In a series of Ba-based oxonitrido-silicate S-phases (Ba2AlxSi12-xN16-xO2+x) spanning a compositional range up to x approximate to 3, we examine the incorporation of Al and O by Si-29 and Al-27 magic-angle spinning (MAS) solid state nuclear magnetic resonance (NMR) and Al-27 triple-quantum MAS (3QMAS). The 3QMAS spectra reveal Al-27 signals from two distinct structural environments, assigned to AlN4 or AlN3O tetrahedra, respectively, and with their relative amounts depending on the S-phase substitution parameter x. Si-29 NMR show variable fractions of SiN4 and SiN3O environments. The NMR results accord overall with a structural substitution model for which O enters at one crystallographic position (occupied according to N4-xOx), in conjunction with a random Al for Si substitution at two distinct crystallographic positions. This leads to S-phase frameworks built from SiN4, SiN3O, AlN4 and AlN3O tetrahedra.

  • 7.
    Elenius, Måns
    et al.
    Stockholm University, Faculty of Science, Numerical Analysis and Computer Science (NADA) (together with KTH).
    Zetterling, Fredrik
    Dzugutov, Mikhail
    KTH, MSE.
    Fredrickson, Daniel
    Department of Chemistry, University of Wisconsin.
    Lidin, Sven
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Department of Inorganic Chemistry.
    Structural model for octagonal quasicrystals derived from octagonal symmetry elements arising in beta-Mn crystallization of a simple monatomic liquid2009In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 79, no 14, p. 144201-1-144201-10Article in journal (Refereed)
    Abstract [en]

    While performing molecular-dynamics simulations of a simple monatomic liquid, we observed the crystallization of a material displaying octagonal symmetry in its simulated diffraction pattern. Inspection of the atomic arrangements in the crystallization product reveals large grains of the beta-Mn structure aligned along a common fourfold axis, with 45° rotations between neighboring grains. These 45° rotations can be traced to the intercession of a second crystalline structure fused epitaxially to the beta-Mn domain surfaces, whose primitive cell has lattice parameters a=b=c=a_{beta-Mn}, alpha =beta =90°, and gamma =45°. This secondary phase adopts a structure which appears to have no known counterpart in the experimental literature, but can be simply derived from the Cr3Si and Al3Zr4 structure types. We used these observations as the basis for an atomistic structural model for octagonal quasicrystals, in which the beta-Mn and the secondary phase structure unit cells serve as square and rhombic tiles (in projection), respectively. Its diffraction pattern down the octagonal axis resembles those experimentally measured. The model is unique in being consistent with high-resolution electron microscopy images showing square and rhombic units with edge-lengths equal to that of the beta-Mn unit cell. Energy minimization of this configuration, using the same pair potential as above, results in an alternative octagonal quasiperiodic structure with the same tiling but a different atomic decoration and diffraction pattern.

  • 8. Fredrickson, Daniel C.
    et al.
    Lee, Stephen
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    Hoffmann, Roald
    Interpenetrating polar and nonpolar sublattices in intermetallics: The NaCd2 structure2007In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 46, no 12, p. 1958-1976Article, review/survey (Refereed)
  • 9. Kocsis, L.
    et al.
    Mink, Janos
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    Jalilehvand, F.
    Laffin, L. J.
    Berkesi, O.
    Hajba, L.
    Vibrational spectroscopic study of the hydrated platinum(II), palladium(II) and cis-diammineplatinum(II) ions in acidic aqueous solutions2009In: Journal of Raman Spectroscopy, ISSN 0377-0486, E-ISSN 1097-4555, Vol. 40, no 5, p. 481-490Article in journal (Refereed)
    Abstract [en]

    Mid infrared, far-infrared and Raman spectroscopic studies, combined with force field analyses, were performed for the 1 hydrated platinum(II) and palladium(II) ions and cis-diammineplatinum(II) complex in acidic aqueous solutions. Simplified Density Functional Theory (DFT) calculations were made for the equatorial plane of the platinum complexes. Careful subtraction of solvent spectra allowed a number of 'internal' modes of coordinated H2O and NH3 to be determined as weak residual bands. The [Pt(OH2)(6)](2+) and [cis-Pt(NH3)(2)(OH2)(4)](2+) complexes were found to be six-coordinated with four ligands strongly bound in an equatorial plane. The assignments of the vibrational modes in the equatorial plane could be performed on the basis of the experimental observations and by comparison with metal-ligand vibrations of square-planar complexes, aided by normal coordinate calculations. For the weakly coordinated axial aqua ligands, the low wavenumber range and the polarizibility properties allowed the assignments of the bands at about 365 and 325 cm(-1) to the stretching modes of one short and one longer Pt - O* bound to axial aqua ligands, respectively. A similar picture with even less strongly bound axial water molecules emerges from Raman spectroscopy data for the hydrated palladium(II) ion, [Pd(OH2)(6)](2+). The results are consistent with a description of the [Pt(OH2)(6)](2+) and [Pd(OH2)(6)](2+) aqua ions in C-4v symmetry, and with the [cis-Pt(NH3)(2)(OH2)(4)](2+) complex in the Cs point group, and also in qualitative agreement with the structures devised from previous extended X-ray absorption fine structure (EXAFS) measurements.

  • 10. Lin, Yuan-Hua
    et al.
    Liu, Yong
    Zhang, Bo-Ping
    Nan, Ce-Wen
    Li, Jing-Feng
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    Electrical transport properties of La2CuO4 ceramics processed by the spark plasma sintering2007In: Journal of The American Ceramic Society, ISSN 0002-7820, E-ISSN 1551-2916, Vol. 90, no 12, p. 4005-4008Article in journal (Refereed)
    Abstract [en]

    Highly dense La2CuO4 ceramics have been prepared by the spark plasma sintering technique. Temperature dependence of electrical conductivity indicates that La2CuO4 ceramics sintered at over 875 degrees C exhibit a metal-like behavior, which should be ascribed to the special La2CuO4 crystal structure and its correlation splitting of the half-filled d(x2-y2) band. Our experimental data indicate that all of the La2CuO4 samples exhibit positive thermoelectric power in the whole measuring temperature range, indicating that the majority of charge carriers are holes. It is desirable to obtain good thermoelectric performance for this system by optimizing the electrical properties and reducing the thermal conductivity.

  • 11.
    Liu, Jing
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    Yan, Haixue
    Reece, Michael J.
    Kan, Yanmei
    Wang, Peiling
    Dielectric, piezoelectric, and ferroelectric properties of grain-orientated Bi3.25La0.75Ti3O12 ceramics2007In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 102, no 10, p. 104107-Article in journal (Refereed)
    Abstract [en]

    By dynamic forging during Spark Plasma Sintering (SPS), grain-orientated ferroelectric Bi3.25La0.75Ti3O12 (BLT) ceramics were prepared. Their ferroelectric, piezoelectric, and dielectric properties are anisotropic. The textured ceramics parallel and perpendicular to the shear flow directions have similar thermal depoling behaviors. The d(33) piezoelectric coefficient of BLT ceramics gradually reduces up to 350 degrees C; it then drops rapidly. The broadness of the dielectric constant and loss peaks and the existence of d(33) above the permittivity peak, T-m, show that the BLT ceramic has relaxor-like behavior.

  • 12.
    Ng, Jovice Boon Sing
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    Kamali-Zare, Padideh
    Division of Cell Physics, Department of Applied Physics, AlbaNova, KTH.
    Sörensen, Malin
    YKI, Institute of Surface Chemistry.
    Alberius, Peter
    YKI, Institute of Surface Chemistry.
    Brismar, Hjalmar
    Division of Cell Physics, Department of Applied Physics, AlbaNova, KTH.
    Hedin, Niklas
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    Bergström, Lennart
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    Intraparticle Transport and Release of Dextran in Silica Spheres with Cylindrical Mesopores2010In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 6, no 1, p. 466-470Article in journal (Refereed)
    Abstract [en]

    The transport of oligomeric molecules in silica spheres with cylindrical mesopores has been quantified and related to the features of the internal structures in the spherical particles and the interactions at the polymer-pore interface. An emulsion-solvent-evaporation method was used to produce silica spheres having cylindrical mesopores with an average pore diameter of 6.5 nm. The transport of dextran molecules (fluorescently tagged) with molecular weights of 3000 and 10000 g/mol were quantified using confocal laser scanning microscopy (CLSM). The intraparticle concentrations profiles in the dextran-containing spheres were flat at all times, suggesting that the underpinning diffusion is not fully isotropic and the release is controlled by the pores close to the external surface of the spheres. The release of dextran into the solution is characterized by an initial burst, followed by a long-term sustained release. This behaviour cannot be described by a spherical model with a single diffusion constant (or a surface-induced mass transfer resistance). The release follows a logarithmic time-dependency that can be described by a Temkin model.

  • 13.
    Nilsson, Göran
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    Svensson, Gunnar
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Structural Chemistry.
    Crystal Structure of BaNb6.3(1)Ti3.6(1)O16 containing Nb6O12, fused Ti3O13 Clusters and Ti3O10 Units2000In: Zeitschrift für Anorganische und Allgemeines Chemie, ISSN 0044-2313, E-ISSN 1521-3749, Vol. 626, no 1, p. 160-172Article in journal (Refereed)
    Abstract [en]

    A new phase, BaNb6.3(1)Ti3.6(1)O16, has been synthesised. Electron diffraction studies indicate an hexagonal substructure with unit cell parameters a ≈ 8.9 Å and c ≈ 9.5 Å. In some of the ED patterns superstructure reflections are present, indicating a supercell with a = √3 · asub and c = csub. However, X-ray single-crystal diffraction studies of a crystallite yielding reflections corresponding to the supercell revealed it to be monoclinic, with the unit cell parameters a = 26.811(2) Å, b = 15.4798(2) Å, c = 9.414(2) Å, β = γ = 90° and α = 90.0(3)°. The average crystal structure was refined, using the subcell with a = 8.937(2) Å, b = 15.479(2) Å, c = 9.414(2) Å, β = γ = 90° and α = 90.0(3)°, space group Cm11, and Z = 4, to RI = 3.24% and RwI = 3.44%. The structure can be described as an hexagonal close packing layers of Nb6 octahedra, Ba, and O atoms (A1, A2) and layers of O atoms (B1, B2), appearing in the packing sequence: A1B1A2B2. The Nb6 octahedra are found in isolated Nb6O12O6 clusters, and the Ti atoms in Ti3O13 and Ti3O10 units in octahedral and tetrahedral voids formed by O atoms, respectively. The Ti positions were found to be only partly occupied. Microanalysis indicates that some Nb atoms are located in the Ti3 triangles. A model is presented that interprets these not fully occupied Ti3 triangles as a result of a superimposing of three different structures. Two of these consist of two fused Ti3O13 units, forming an Ti6O19 unit, and a Ti3O10 unit, while the third consists of alternating Ti3O13 units.

  • 14.
    Nygren, Mats
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    SPS processing of nano-structured ceramics2007In: Journal of Iron and Steel Research International, ISSN 1006-706X, E-ISSN 2210-3988, Vol. 14, p. 99-103Article in journal (Refereed)
    Abstract [en]

    All sintering techniques have their advantages and disadvantages. In this contribution it will be shown that the SPS technique is very well suited for the task to prepare nano-structured ceramics. In this contribution the processing strategy used to obtain nano-sized ceramics of Bi4Ti3O12, BaTiO3, and SrTiO3, respectively, will be discussed in some detail and outline the procedure that allow us to define a ""kinetic window"" within which it is possible to densify these nano-powders into fully dense compacts containing grains of almost the same size as the staring powders. We have up to day consolidated some 20 different of nano-sized powders into fully dense compacts having grain sizes exceeding those of the starting powders by factors ranging from 1.5 to 6. The grain growth factor varies with the grain size of the starting powder, i.e. if the starting powder has a grain size in the range 60-100 nm the obtained compacts normally have grain sizes in the range of 150-250 nm. With decreasing grain size of the starting powder, e. g. 10-30 run, the grain growth factor is increasing from 1.5-2.5 to 4-6. These observations are in line with the common knowledge that the driving force for reduction of the interfacial area is much smaller for 100 run sized precursor powders than for 10 nm ones.

  • 15.
    Piao, Shuying
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    Lidin, Sven
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    A New Compound in the Cu-In System: the Synthesis and Structures of Cu10In72008In: Zeitschrift für Anorganische und Allgemeines Chemie, ISSN 0044-2313, E-ISSN 1521-3749, Vol. 634, no 14, p. 2589-2593Article in journal (Refereed)
    Abstract [en]

    A new binary phase, Cu10In7, was found during the investigation of the eta-phase field in the Cu-In system. Single crystals Cu10In7 were grown from a melt under an inert atmosphere. The compound crystallizes in the monoclinic space group C2/m with cell parameters a = 13.8453(2) angstrom, b = 11.8462(1) angstrom, c = 6.7388(1) angstrom and beta = 91.063(1). The structure is based on a unit of face-sharing octachedra consisting of five Cu4In2 octahedra terminated by Cu5In octahedra at both ends. The crystal Structure is closely related to the Cu11In9 structure type.

  • 16.
    Ponou, Simeon
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    Lidin, Sven
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    Synthesis and Crystal Structure of Ca2Ag1.83Al0.67Ge1.50: A Solid Solution with the NbCoB-type structure2009In: Zeitschrift für Anorganische und Allgemeines Chemie, ISSN 0044-2313, E-ISSN 1521-3749, Vol. 635, no 13-14, p. 2143-2146Article in journal (Refereed)
    Abstract [en]

    The crystal structure of the new phase, Ca2Ag1.83Al0.67Ge1.50 (1) (1) was determined by single-crystal X-ray diffraction, after the compound was obtained by high temperature synthesis technique. 1 crystallizes with the NbCoB type structure in the orthorhombic space group Pmmn (no. 59) with unit cell parameters: a = 20.505(1) angstrom, b = 4.3807(2) angstrom, c = 7.2211(3) angstrom, V = 648.65 angstrom(3) (Z = 5). The structure of the title compound represent a rare intergrowth of the well known KHg2 (or CeCu2) and Fe2P type structures.

  • 17.
    Tengå, Andreas
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    Lidin, Sven
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Belieres, Jean-Phillippe
    Arizona State University.
    Newman, Nathan
    Arizona State University.
    Wu, Yang
    Arizona State University.
    Häussermann, Ulrich
    Arizona State University.
    Cd13-xInySb10 (x approximate to 2.7, y approximate to 1.5): An Interstitial-Free Variant of Thermoelectric beta-Zn4Sb32009In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 15, no 27, p. 6704-6710Article in journal (Refereed)
    Abstract [en]

    Although free from structural disorder, the new intermetallic compound Cd13−xInySb10 (see figure) displays similarly low thermal conductivity values as disordered thermoelectric β-Zn4Sb3 with an isostructural framework.

    Cd13−xInySb10 (x≈2.7, y≈1.5) was synthesized in the form of mm-sized crystals from reaction mixtures containing excess cadmium. The intermetallic compound crystallizes in the rhombohedral space group Rm with a=12.9704(4), c=12.9443(5) Å, V=1886.0(1) Å3, Z=3 and is isostructural to thermoelectric β-Zn4Sb3 and β-Cd4Sb3. However, in contrast to these last two compounds Cd13−xInySb10 is free from interstitial atoms and does not display any temperature polymorphism. The electrical resistivity of Cd13−xInySb10 is considerably higher than that of Zn4Sb3 and Cd4Sb3 although the temperature behavior remains that of a metal. The thermal conductivity of Cd13−xInySb10 is low, with room-temperature magnitudes around 0.8 W m−1 K−1, which is comparable to disordered or complex structured Cd4Sb3 and Zn4Sb3.

  • 18. Wang, Jing
    et al.
    Wang, Lianjun
    Liu, Guanghua
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Substrate effect on the magnetoelectric behavior of Pb(Zr0.52Ti0.48)O3 film-On-CoFe2O4 bulk ceramic composites prepared by direct solution spin coating2009In: Journal of The American Ceramic Society, ISSN 0002-7820, E-ISSN 1551-2916, Vol. 92, no 11, p. 2654-2660Article in journal (Refereed)
    Abstract [en]

    Magnetoelectric (ME) composite structures of Pb(Zr0.52Ti0.48)O3 (PZT) and CoFe2O4 (CFO) were prepared by directly growing PZT films on highly dense CFO ceramics via a simple solution spin coating, rather than by conventional high-temperature cofiring. An obvious ME response, which had the same bias-dependent trend as the piezomagnetic coefficient of CFO ceramics, was observed in such film-on-bulk ceramic composites. It was found that the PZT films showed a good ferroelectric feature, and the ME response of the composites strongly depended on the resistivity of the CFO ceramics as both a substrate and a bottom electrode. The results suggest plenty of room for further enhancing the ME response of such films-on-ceramic substrate composites.

  • 19.
    Wijk, Maria
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    Synthesis and characterisation of heterobimetallic erbium alkoxides1997Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis describes the synthesis and characterisation of alkoxides in the Er-M systems, where M = Al, Ti and Zr. The compounds found have been characterised by IR, UV-Vis DSC and single-crystal X-ray diffraction techniques and by chemical behaviour. It is shown that UV-Vis spectra can be used as an analytical tool to distinguish between different Er-containing alkoxides.

    Two homometallic erbium isopropoxides have been synthesised. The first (1) is assumed to be a solvated non-oxo-alkoxide, which decomposes almost quantitatively to Er5O(OPri)13 when it is evaporated or partially hydrolysed. Er5O(OPri)13 can also be synthesised directly in high yields, using a reaction that involves partial hydrolysis. The reactivity of Er5O(OPri)13 is demonstrated by the reaction with Al4(OPri)12. The Nd analogues are also presented.

    The structures of two different compounds in the Er-Al-isopropoxide system have been determined: Er2Al2(OPri)12(HOPri)2 and ErAl3(OPri)12, and a fourth[SGIW1] compound with the approximate Er-to-Al ratio 3:1 has also been found. ErAl3(OPri)12 could be syntesised using Er5O(OPri)13 as erbium source. This reaction was monitored by UV-Vis measurements and by IR studies of evaporated samples at different stages in the reaction. In the Er-Ti-ethoxide system only one compound could be isolated: Er2Ti4O2(OEt)18(HOEt)2, and partial hydrolysis was necessary in order to reach high yields. Synthesis under strictly anhydrous conditions produced only non-isolable compound(s). When using isopropanol in stead of ethanol, another oxo-alkoxide was formed: Er4TiO(OPri)13.

    In the Er-Zr-isopropoxide system, the compound Er2Zr2O(OPri)12(HOPri)3 is obtained both under anhydrous conditions and after partial hydrolysis. No alkoxides with higher Zr content are formed in this system.

    Most of the structural fragments, i.e. the M-O core structures (M = Er, Al, Ti and Zr) found in the different erbium-containing alkoxides, are rather common in both homometallic and heterometallic alkoxides. Examples of these fragments are: the square pyramidal M5O core, the C2h configuration (M4O62) and the "butterfly configuration" (M4O). Er2Al2(OPri)12(HOPri)2 is exceptional in containing the rarely seen linear arrangement of the M-O core.

  • 20. Wójcik, N. A.
    et al.
    Jonson, B.
    Möncke, D.
    Palles, D.
    Kamitsos, E. I.
    Ghassemali, E.
    Seifeddine, S.
    Eriksson, Mirva
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Inorganic Chemistry.
    Ali, S.
    Influence of synthesis conditions on glass formation, structure and thermal properties in the Na2O-CaO-P2O5 system doped with Si3N4 and Mg2018In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 494, p. 66-77Article in journal (Refereed)
    Abstract [en]

    Oxynitride phosphate glasses and glass-ceramics were prepared using new synthesis routes for phosphate glasses. Materials were melted from pre-prepared glass samples in the system Na-Ca-P-0 with addition of Mg and/or Si3N4 powders under different preparation conditions. The melting process was conducted at 1000-1500 degrees C either under air or nitrogen atmosphere to obtain materials with different nitrogen content. Their topography and structure were characterized by Confocal Microscopy, Scanning Electron Microscopy, X-ray powder diffraction and Raman and infrared spectroscopy techniques, while their chemical compositions were examined by Energy Dispersive X-ray spectroscopy (EDS). All materials prepared under nitrogen atmosphere were found to contain a relative low quantity of nitrogen and high amount of Nb leached from the crucible. The reaction with the Nb crucible was not previously observed for silicon-based oxynitride glasses. The synthesized materials form two groups: glasses and glass-ceramics. The first ones, were prepared under air and nitrogen atmospheres at temperatures up to 1400 degrees C, and were found to be amorphous and homogeneous. Raman and infrared spectroscopy measurements confirm the presence of amorphous phosphates in the synthesized materials. The samples of the second group were prepared at temperatures above 1400 degrees C and were found to be translucent and partially crystallized. They contain nanocrystallites of calcium and sodium phosphates including hydroxyapatite (HAp). The thermal properties of samples were studied by Differential Scanning Calorimetry (DSC). The obtained glass transition temperatures range from about 360 degrees C to 640 degrees C and exhibit high values for glass-ceramic materials. Stability is improved in the studied glass-ceramics because of the increased degree of network polymerization of the remaining glassy matrix. The approximate fragility index decreases two times for oxynitride materials compared to the primary glass. The synthesized new materials may be competitive to well-known bioactive phosphate glasses thanks to their improved stability by Mg, Si, N and Nb doping.

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