TILTING AND DISTORTION OF CASNO3 PEROVSKITE TO 7 GPA DETERMINED FROM SINGLE-CRYSTAL X-RAY DIFFRACTION

Abstract

The structural changes of CaSnO3, a GdFeO3-type perovskite, have been investigated to 7 GPa in a diamond-anvil cell at room temperature using single-crystal X-ray diffraction. Significant changes are observed in both the octahedral Sn-O bond lengths and tilt angles between the SnO6 octahedra. The octahedral (SnO6) site shows anisotropic compression and consequently the distortion of SnO6 increases with pressure. Increased pressure also results in a decrease of both of the inter-octahedral angles, ∠Sn-O1-Sn and ∠Sn-O2-Sn, indicating that octahedral tilting increases with increasing pressure, chiefly equivalent to rotation of the SnO6 octahedra about the pseudocubic <001>p axis. The distortion in the CaO12 and SnO6 sites, along with the octahedral SnO6 tilting, is attributed to the SnO6 site being less compressible than the CaO12 site.