High-pressure structural phase transitions in RuO2 and its geophysical implications

We studied the high-pressure behaviour of RuO2 and compared with that of it s analogue SiO2. The high-pressure stability of Pa (3) over bar phase as co mpared to fluorite (CaF2) phase has been supported through our calculations , which is in full agreement with recent experimental results. On compressi on, we predicted the presence of a high-pressure (CaF2) type RuO2. The calc ulated pressure for the phase transition is around 65 GPa. We reported the presence of Pa (3) over bar type of phase in RuO2 at lower pressures as com pared to SiO2, which may be due to the absence of alpha -PbO2 (Pnc2) type o f phase in RuO2. (C) 2001 Elsevier Science Ltd. All rights reserved.