Characterization of the 100 K phase transition in SrTiO3by means of high-resolution γ-ray diffractometry

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Abstract
The nature of the bulk phase transition in SrTiO3 at 100 K has been studied by high-resolution γ-ray diffractometry using 316 and 468 keV photons. After strain-free mounting of a top-seeded single crystal (approximately 1 cm3 in dimensions) the observed change of the intensity of the photons Bragg scattered at a main reflection enforces the continuous nature of this phase transition. The dependence of the measured intensity on the cooling/heating cycle is caused by different domain formations. No distinct precursor effect due to structural inhomogeneities could be observed. An analysis of the diffraction patterns measured above Tc suggests that about 95% of the crystal volume is highly perfect with an alignment of the lattice planes to better than 0.2″. A skin layer of ≃0.2 mm thickness with a mosaic spread of ≃7″ may account for 80% of the total scattering above Tc .