Mössbauer effect in the system Ca₂Fe₂O₅-Ca₂FeAlO₅

Abstract

Mossbauer spectra were measured on Ca₂Fe₂O₅, Ca₂Fe_1.5Al_0.5O₅, Ca₂FeAlO₅, and Ca₂Fe_0.67Al_1.33O₅ at temperatures from 95°K to above the Neel points. The Mossbauer spectrum of Ca₂Fe₂O₅ below its Neel point shows lines which were assigned to tetrahedral and octahedral site ferric ions on the basis of the observed isomer shifts and hyperfine splittings. The Mossbauer spectra of the aluminium-substituted calcium ferrites give unequivocal evidence that the aluminium goes preferentially into tetrahedral sites. A four-sublattice magnetic structure is suggested for Ca₂Fe₂O₅.