X-Ray Diffractometry of Low-Temperature Phase Transformations in Strontium Titanate

Abstract

The lattice parameters of single-crystal SrTiO3 were determined by x-ray diffraction as a function of temperature from 4.2° to 300°K. In addition to the normal cubic structure three significant regions were found. From 65° to 100°K a tetragonal modification exists (c/a=1.00056), from 35° to 55°K line splitting consistent with orthorhombic symmetry was observed, and at 10°K an anomalous maximum in the lattice parameter vs temperature curve was found which suggested a third structure transformation. In the tetragonal region (at 78°K) various domain configurations were photographed with a polarizing microscope.