Generalized gradient approximation calculations of the pressure-induced phase transition of YAlO(3) perovskite.

An investigation into the high-pressure behaviour of YAlO(3) perovskite was conducted using first-principles calculations based on density functional theory within the generalized gradient approximation. Five candidate phases were considered, Pbnm, Cmcm, I4/mcm, P4/mbm and Pm3m respectively. Our results demonstrate a phase transition of YAlO(3) from Pbnm to I4/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 YAlO(3) is similar to that of CaSiO(3). The pressure dependence of the distortion of AlO(6) 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.