X-ray diffuse scattering in SrTiO₃ and model of atomic displacements

The scattering intensity of synchrotron radiation in a compact three-dimensional volume of the reciprocal space of an SrTiO₃ single crystal has been measured. The diffuse pattern cannot be explained by a simple chain of just one of the displaced cations but is compatible with the displacements of Sr²⁺ along [001]_cub (where the subscript cub denotes the cubic structure) correlated in the same direction and with simultaneous displacements of Ti⁴⁺ along [111]_cub, or alternatively along [011]_cub or [101]_cub, while the displacements of Ti⁴⁺ are correlated along [001]_cub.