Structural investigation of LaAlO3 up to 63 GPa.

We report a high-pressure synchrotron x-ray diffraction on a LaAlO(3) single crystal. The transition from rhombohedral to cubic at 14.8 GPa is confirmed by the loss of the superstructure reflections, whose intensity shows a linear pressure dependence, characteristic of a second-order transition. The crystal remains cubic up to 63 GPa, the highest pressure reached, which provides a confirmation over a very large pressure range of the general rules for the evolution of distortions of perovskites under pressure. We report the parameters of the Birch-Murnaghan equations of state in the low- and high-pressure phases and discuss the evolution of the bulk modulus.