Mössbauer spectroscopy as a probe of magnetic states in La0.5Ca0.5FeO3−δ perovskite

Charge disproportionation in La_0.5Ca_0.5FeO_3−δ perovskite has been detected by zero-field Mössbauer spectra from 20 K to room temperature. On the basis of the parameters of center shifts and hyperfine fields, Mössbauer spectra identified that the iron ionic states are Fe³⁺ and Fe⁵⁺ below 150 K, Fe³⁺, Fe⁴⁺ and Fe⁵⁺ in the intermediate temperature region, as well as Fe³⁺ and Fe⁴⁺ above 220 K. At low temperatures, the system exhibits a cluster-glass-like state resulting from competition between antiferromagnetic interaction of Fe³⁺–Fe³⁺ and ferromagnetic interaction of Fe³⁺–Fe⁵⁺.