Investigation of the crystal and magnetic structure of the perovskite system Sr2FeTiO6 –y by Mössbauer spectroscopy and neutron diffraction

Abstract

The crystal structure of the cubic perovskite Sr₂FeTiO_5.81 has been refined in space group Pmm using neutron powder diffraction data collected at 2 K. There is no evidence for long-range magnetic order. Mössbauer and magnetic susceptibility data show a phase transition in the vicinity of 20 K which has been interpreted in terms of spin-glass behaviour. The long-range structural disorder of the B-site cations, and the mixed oxidation states of the iron (shown to be Fe³⁺ and Fe⁴⁺) lead to incompatible superexchange interactions and frustration of the spin system in establishing long-range order.