X-ray diffuse scattering in SrTiO3and model of atomic displacements

Abstract

The scattering intensity of synchrotron radiation in a compact three-dimensional volume of the reciprocal space (sinθmax/λ = 0.6283 Å−1) of an SrTiO3single crystal has been measured at temperatures of 115, 130 and 293 K. The curvilinear features of the diffuse pattern were modelled according to the displacements of both cations correlated along the axis [001]cub(where the subscript cub denotes the cubic structure). The results show that Sr2+is displaced from the ideal positions along the crystallographic axis [001]cub, forming a short chain composed of about three Sr2+ions along [001]cub, while the Ti4+ions are moved in the directions [111]cub, or alternatively [101]cubor [011]cub. The Ti4+displacements are also correlated along [001]cub, forming a similarly short chain.