Mössbauer effect in the system Ca2Fe2O5-Ca2FeAlO5

Abstract

Mossbauer spectra were measured on Ca2Fe2O5, Ca2Fe1.5Al0.5O5, Ca2FeAlO5, and Ca2Fe0.67Al1.33O5 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.