Denis Orosel

Graz University of Technology, Gratz, Styria, Austria

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Publications (9)20.37 Total impact

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    ABSTRACT: A quenchable new high-pressure-high-temperature modification of antimony(III) oxide, γ-Sb(2)O(3), has been obtained at hydrostatic pressures of 9-11 GPa and temperatures of 573-773 K. Its crystal structure has been determined from high-resolution synchrotron powder diffraction data. γ-Sb(2)O(3) consists of three-dimensionally cross-linked infinite chains of SbO(3)E units (E = lone pair) with the chains forming tetragonal rod-packing. The underlying topology of γ-Sb(2)O(3) (3,3T8) is found very rarely in inorganic structures; it is realised only for the polyanion [Si(4)O(4)N(6)](10-) that occurs in the Ce(4)(Si(4)O(4)N(6))O structure type. The structural relation to the two previously known polymorphs of Sb(2)O(3) at ambient pressure, valentinite and senarmontite is discussed.
    No preview · Article · Feb 2012 · Acta crystallographica. Section B, Structural science
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    ABSTRACT: A piezoelectric multilayer device based on bismuth–sodium–titanate ceramics (BNT) co-fired with Ag/Pd inner electrodes is described and its dielectric and piezoelectric properties are measured. The ceramic powder and tape was made by a water-based preparation process. After printing with Ag/Pd paste for inner electrodes these tapes were stacked to a multilayer device with 50 active layers. This device exhibited a large and temperature independent strain around 0.19% between 25°C and 150°C. The large strain is due to a field-induced phase transition. The low temperature dependence results from the broadening of the nonpolar phase by doping.
    No preview · Article · Aug 2011 · Journal of the European Ceramic Society
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    ABSTRACT: We report on a new mixed valence arsenic(III,V)oxoacid H6As73+As75+O31 which crystallizes in the hexagonal space group P6(3) (no. 173), with lattice parameters a = 12.0525(1) angstrom, c = 4.7344(l) angstrom, v = 595.6(1) angstrom(3) and Z = 2. This phase is metastable and upon heating the RT-phase of As2O5 is recovered. The structure exhibits the first As5+ atom with a fivefold coordination by oxygen atoms in the shape of a distorted square pyramid. The positions of the hydrogen atoms were determined during the structure refinement from high resolution synchrotron powder diffraction data by difference Fourier analysis.
    No preview · Article · Jul 2007 · Zeitschrift für Kristallographie
  • P. Balog · D. Orosel · Z. Cancarevic · C. Schön · M. Jansen
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    ABSTRACT: New experiments on V2O5 have been performed using large volume high pressure and high temperature devices, to pressures up to 29 GPa and temperatures up to 1500 °C. Post-temperature and pressure quench, samples have been structurally analysed using X-ray diffraction and Raman spectroscopy. Data obtained confirms earlier experimental results at elevated pressures and temperatures, and reveals the stability range of the high-pressure phases far beyond the previously known region. Rietveld refinement of the δ-phase of V2O5 shows that the phase crystallizes in space group C12/c1 (no. 15) with a = 11.9719(2) Å, b = 4.7017(1) Å, c = 5.3253(1) Å, β = 104.41(0)°, V = 290.32(7) Å3 and Z = 4. The tentative mapping of phase boundaries is also in agreement with our theoretical predictions for pressure-induced transitions at absolute zero temperature.
    No preview · Article · May 2007 · Journal of Alloys and Compounds
  • Denis Orosel · Robert Dinnebier · Martin Jansen
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    ABSTRACT: We report on the first synthesis of a potassium orthoselenate(VI), K6(SeO4)(SeO5), and the structure determination from synchrotron powder diffraction data. The title compound crystallizes in the tetragonal space group P41212 with a = 8.1259(1) A, c = 17.4953(2) A, V = 1155.21(2) A3, and Z = 4. Selenium displays two different complex anions, tetrahedral SeO42- and trigonal-bipyramidal SeO54-. When the formula is reduced to A3B, the spatial arrangement of the constituting building units can be derived from the Li3Bi type of structure.
    No preview · Article · Apr 2007 · Inorganic Chemistry
  • Denis Orosel · Martin Jansen
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    ABSTRACT: Ssolid state reaction of palladium(II) oxide (PdO) and arsenic(V) oxide (As2O5) yielded an auburn colored microcrystalline powder of palladium(II) metaarsenate(V), PdAs2O6. The crystal structure of the compound belongs to the PbSb2O6 structure type, P (3) over bar 1m (no. 162), a = 4.8196(0) angstrom, c = 4.6646(l) angstrom, V = 93.84(0) angstrom(3) and Z = 1. The structure consists of layers of edge sharing AsO6 octahedra and PdO6 octahedra connecting them. This is one of the rare structures with divalent palladium in octahedral coordination by oxygen. The compound is paramagnetic and shows antiferromagnetic ordering at about 150 K, which is 5 times higher than that of the isotypic NiAs2O6 compound.
    No preview · Article · Aug 2006 · ChemInform
  • Denis Orosel · Martin Jansen
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    ABSTRACT: PdAs2O6, the First Paramagnetic Palladium Oxide Ssolid state reaction of palladium(II) oxide (PdO) and arsenic(V) oxide (As2O5) yielded an auburn colored microcrystalline powder of palladium(II) metaarsenate(V), PdAs2O6. The crystal structure of the compound belongs to the PbSb2O6 structure type, (no. 162), a = 4.8196(0) Å, c = 4.6646(1) Å, V = 93.84(0) Å3 and Z = 1. The structure consists of layers of edge sharing AsO6 octahedra and PdO6 octahedra connecting them. This is one of the rare structures with divalent palladium in octahedral coordination by oxygen. The compound is paramagnetic and shows antiferromagnetic ordering at about 150 K, which is 5 times higher than that of the isotypic NiAs2O6 compound.
    No preview · Article · Jun 2006 · Zeitschrift für anorganische Chemie
  • D. Orosel · P. Balog · H. Liu · J. Qian · M. Jansen
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    ABSTRACT: Investigations on Sb{sub 2}O{sub 4} at high pressure and temperature have been performed up to 600{sup o}C and up to 27.3GPa. The so-called 'high temperature' phase ({beta}-Sb{sub 2}O{sub 4}) was obtained following pressure increase at ambient temperature and at relatively low temperatures. Thus, in contrast to previous perceptions, {beta}-Sb{sub 2}O{sub 4} is the modification more stable at high pressures, i.e., at low temperatures. The fact that the metastable {alpha}-form is typically obtained through the conventional way of preparation has to be attributed to kinetic effects. The pressure-induced phase transitions have been monitored by in-situ X-ray diffraction in a diamond anvil cell, and confirmed ex-situ, by X-ray diffraction at ambient conditions, following temperature decrease and decompression in large volume devices. Bulk modulus values have been derived from the pressure-induced volume changes at room temperature, and are 143GPa for {alpha}-Sb{sub 2}O{sub 4} and 105GPa for the {beta}-Sb{sub 2}O{sub 4}.
    No preview · Article · Sep 2005 · Journal of Solid State Chemistry
  • D Orosel · O Leynaud · P Balog · M Jansen
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    ABSTRACT: We have investigated SeO2 at high pressures and high temperatures. Two new phases (β-SeO2 and γ-SeO2) and the boundary separating them have been found, following experimental runs performed at pressures up to 15 GPa and temperatures up to 820°C. The two phases crystallize in the orthorhombic system in space group Pmc21 (no. 26) with a=5.0722(1) Å, b=4.4704(1) Å, c=7.5309(2) Å, V=170.760(9) Å3 and Z=4 for the β-phase, and with a=5.0710(2) Å, b=4.4832(2) Å, c=14.9672(6) Å, V=340.27(3) Å3 and Z=8 for the γ-phase. Both phases are stable at ambient pressure and temperature below −30°C. At ambient temperature the phases return to the starting phase (α-SeO2) in a few days. We discuss our findings in relation to a previous report of in-situ measurements at high pressures and ambient temperature.
    No preview · Article · Apr 2004 · Journal of Solid State Chemistry