Precursor synthesis and magnetic properties of Cd1-xFexO (0 ≤ x ≤ 0.07) polycrystalline solid solutions

Abstract

Polycrystalline solid solutions Cd1-xFexO (0 < x ≤ 0.07) have been synthesized by the precursor method using formate of the composition Cd1-xFex(HCOO)2·2H2O as a precursor. For the production of Cd1-xFexO, the precursor was annealed in air at a maximal temperature of 400 °C. At x ≥ 0.075, an impurity CdFe2O4 ferrite phase with cubic spinel structure was detected in the samples. The examination of the magnetic properties of Cd1-xFexO at 5 and 300 K revealed that they are ferromagnets, whose magnetization increases with the concentration of iron both at low and room temperature reaching the maximal values in samples with х = 0.07. In order to determine the degree of oxidation and the spin state of iron atoms, the main interatomic interactions giving rise to ferromagnetism as well as to estimate the Curie temperatures, we also performed first-principle calculations of the electronic band structure. They showed the existence of chemical bonding between adjacent iron atoms leading to the appearance of ferromagnetism by direct exchange. The value of the Curie temperature calculated by the mean field method on the basis of the first-principle calculations is 507 K, which is in reasonable agreement with the experimental value of 560 K.