Effect of Fe ⁴⁺ in the System SrFeO ₃ ‐SrTiO ₃

Perovskites of the system SrFeO 3 ‐SrTiO 3 were prepared, and measurements were made of their magnetic and electrical behavior. Chemical analysis showed that the percentage of Fe 4+ varied from 72.5% for SrFeO 2.86 to about zero for Sr(Fe 0.1 Ti 0.9 )O 2.95 ; the remainder of the iron was in the Fe 3+ state and electrical balance was achieved by oxygen loss. Sr(Fe 1‐ x Ti x )O 3 was antiferromagnetic between x = 0 and x = 0.9, with a Néel temperature below 60°K. A parasitic ferromagnetic component developed when these compounds were cooled in a magnetic field, the magnitude of this component being dependent on the cooling field. The conductivity of these perovskites ranged from 10 −8 ohm −1 cm −1 for x = 1.0 to 10 −2 for x = 0.0 and showed a marked change at x = 0.8. The break corresponded to a change in slope of the lattice parameter and the disappearance of Fe 4+ . The Fe 4+ content depended on the heat treatment and atmosphere during formation.