Abstract
A new high pressure modification VO2(S) was obtained by the thermobaric treatment of stoichiometric mixture of powders V2O3+V2O5 at Р = 2.0–7.0 GPa and Т = 600–900°С. The crystal structure of VO2(S) has been studied using X-ray powder diffraction: a = 7.35367(3), c = 4.51507(4) Å, V = 211.448(1) Å3 at T = 296(1) K, Z = 7, space group P3. The V atoms are six-coordinated within distorted VO6 octahedra. The structure is double-layered and built up of triple units of edge-shared octahedra. The connection of these units forms one solid layer, while the second one contains separate units. Structural relationships between VO2(S), VO2(M2) and WO2-hp are discussed. Electric and X-ray diffraction measurements show that VO2(S) undergoes a weak first-order phase transition at temperature around 290 K. We also carried out density functional calculations of VO2(S) using the hybrid HSE06 exchange-correlation functional. The charge and heat transport properties are evaluated within the semi-classical Boltzmann approach.
Published Version
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