MOSSBAUER AND MAGNETIC STUDIES OF DICALCIUM FERRITE (CA2FE2O5)

In the antiferromagnetic compound Ca2Fe2O5, the ferric ions occupy two non-equivalent sites. By means of Mössbauer studies in the temperature range 80 to 800 ° K, the variation of the magnetic hyperfine fields at both sites, as a function of temperature, is determined. It is found that all ferric ions order antiferromagnetically at a single Néel temperature, TN=(725±2) ° K. From previous studies, the magnetic point group of this compound is known, and leads one to anticipate the existence of a ferromagnetic component in the ordered state. Magnetic measurements do, in fact, indicate the existence of such a component. The experimental values obtained for the quadrupole splittings at both ferric sites are compared with point charge calculations. This leads to a complete disagreement, both in the ordered region and in the paramagnetic region, showing the inadequacy of the point charge model for the present case. All the results are compared with the results of previous investigations on the same compound. © 1969 Chapman and Hall.