Fe57 Mossbauer Study In Cobalt Substituted Magnetite

Abstract

The Mossbauer effect has been studied in the mixed ferrites CoxFe3_x04 (for x = 0.8, 0.9 and 1) with the spinel structure in the temperature range between 78 and 830K. The composition with x = 1, showed an expected Zeeman spectrum with two overlapping magnetic hyperfine patterns related to the Fe34' ions in tetrahedral and octahedral sites. While for samples with x = 0.8 and 0.9 the Mossbauer spectrum for each compound was successfully analysed into three different patterns corresponding to the ferric ions placed at the tetrahedral and octahedral sites and ferrous ions at the octahedral sites, indicating no electron transfer between Fe^ and Fe24", where the quantity of cobalt sufficiently large to be located at the six nearest neighbours to ferrous ions. The Mossbauer effect parameters were calculated for these observed sites and their variation with temperature reported. The reduced hyperfine magnetic fields of the Fe^ (B) ions were found to follow the one third power law. The magnetic ordering temperature was determined to be == 815 K and the possible magnetic interactions were discussed.