The effects of pressure on the lattice of the rare-earth-based perovskite-type oxides SmAlO3 and NdAlO3

Abstract This paper studies the behavior of SmAlO 3 and NdAlO 3 when they are subject to high pressures. This work is undertaken using angle-dispersive synchrotron x-ray powder diffraction and Raman spectroscopy at pressures up to 24.2 and 39.0 GPa, respectively. It is found that SmAlO 3 undergoes an orthorhombic ( Pnma ) to rhombohedral ( R -3 c ) structure transition at around 10 GPa; this transition is induced by the rotation of the AlO 6 octahedra toward that of the ideal perovskite structure when the material is subject to high pressures. The tilting of the AlO 6 octahedra also decreases at high pressures in NdAlO 3 . It is found that NdAlO 3 maintains its original rhombohedral structure for pressures of up to 39.0 GPa. The structural changes observed in these compounds help establish the electrical and magnetic properties of RAlO 3 (R = Sm or Nd) at high pressures.