X-ray powder diffraction study of CaTiO3 perovskite at high temperatures

CaTiO₃ perovskite has been studied at high temperature and P = 1 bar by powder x-ray diffraction and its structure refined subsequently by the Rietveld method. This Pbnm perovskite shows a decrease of orthorhombic distortion with increasing temperature as manifested by the increasing of the inter-octahedral angles towards 180°. Linear thermal expansion is observed for CaTiO₃ to 1373 K; extrapolation of these data suggest a possible transition to a tetragonal or pseudo-tetragonal phase near 1600 K.A National Science Foundation Science and Technology Center