Crystal synthesis and structure refinement of high-pressure ScAlO3 perovskite

Abstract

Summary: Single crystals of ScAlO₃ perovskite have been synthesized at 3.5 GPa pressure using lithium fluoride as a high-temperature solvent. The crystal structure has been refined by the least-squares method using 498 three-dimensional reflections to a final R value of 0.028. Unit-cell dimensions at ambient conditions (1 bar, 20° C) are a = 4.9355(3), b = 5.2313(3), c = 7.2007(5) Å, with space group Pbnm. The structure differs slightly from the powder refinement, resulting in less distortion of the aluminium octahedron. The space-group confirmation and the more regular octahedron are used as evidence in support of a centrosymmetric structure for the lower-mantle phase MgSiO₃ perovskite.