Variation of crystal structure of SrGeO₃ high-pressure perovskite phase as a function of temperature

Abstract

Single crystals of SrGeO₃ high-pressure perovskite phase have successfully been grown at high-pressure and high-temperature. The single-crystal X-ray diffraction analyses were conducted at seven temperature points in the range of 100 to 323 K. Consequently, the mean square displacement (MSD) of the O atom in the direction of the Ge-O bond is almost temperature-independent, whereas that in the direction perpendicular to the bond largely increases with increasing temperature. This peculiar thermal vibration behavior of the O atom can be due to a strong covalency of the Ge-O bond.