Chinese Acad Sci, Beijing Synchroton Radiat Facil, Inst High Energy Phys, Beijing 100049, Peoples R China
; Peking Univ, Dept Geol, Beijing 100871, Peoples R China
An investigation into the high-pressure behaviour of YAlO3 perovskite was conducted using first-principles calculations based on density functional theory within the generalized gradient approximation. Five candidate phases were considered, Pbnm, Cmcm, 14/mcm, P4/mbm and Pm3m respectively. Our results demonstrate a phase transition of YAlO3 from Pbnm to 14/mcm at 80 GPa and 0 K, and no tendency to the cubic phase or the post-perovskite phase in our pressure range. This high-pressure behaviour of YAlO3 is similar to that of CaSiO3. The pressure dependence of the distortion of AlO6 octahedra is described by the octahedral tilting and rotation angles, the tolerance factor, the polyhedral volume ratio and the valence charge density. We also summarize the relations between tolerance factor, bulk modulus and radius of the A-site in Pbnm-AAlO(3) systems.