V2O5 phase diagram revisited at high pressures and high temperatures

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 degrees 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 delta-phase Of V2O5 shows that the phase crystallizes in space group C12/c1 (no. 15) with a = 11.9719(2) angstrom, b = 4.7017(1) angstrom, c = 5.3253(1) angstrom, beta = 104.41(0)degrees, V= 290.32(7) angstrom(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. (c) 2006 Elsevier B.V. All rights reserved.