Single-crystal X-ray diffraction study of SrGeO3 high-pressure perovskite phase at 100 K

Single-crystal X-ray diffraction study of SrGeO3 perovskite (cubic; space group Pmɜm) synthesized at 6 GPa and 1223 K was conducted at a low temperature of 100 K. The residual electron density revealed the presence of the bonding electron at the center of the Ge–O bond, in accordance with our previous conclusion that the Ge–O bond is strongly covalent. From comparison with our previous structure-refinement result at 296 K, the mean square displacement (MSD) of the O atom in the direction of the Ge–O bond is suggested to exhibit no significant temperature dependence, in contrast to that in the direction perpendicular to the bond. Thus, the strong covalency of the Ge–O bond can have a large influence on the temperature dependence of thermal vibration of the O atom.