V 2O 5 phase diagram revisited at high pressures and high temperatures

Abstract

New experiments on V 2O 5 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 V 2O 5 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) Å 3 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.