Moessbauer studies of Cu1-xNixFeMnO4 spinel ferrites

Nickel copper ferromanganites Cu1-xNixFeMnO4 with the composition (0≤x≤1) have been prepared using a ceramic technique. A single phase of these compounds was confirmed by X-ray powder diffraction measurements. Moessbauer spectra were recorded in 20-628 K temperature range. The spectra of all samples showed two well-resolved Zeeman patterns corresponding to A- and B-sites. At room temperature the hyperfine field increases with decreasing Cu concentration. The cation distribution obtained from analysis of Moessbauer spectra revealed a partially inverse spinel structure. The Curie temperature (TC) increased with the increase of the composition parameters (x). The specific heat Cp for nucleus 57Fe was calculated from Moessbauer data for Cu0.5Ni0.5FeMnO4, and NiFeMnO4. The temperature dependence of the hyperfine parameters was studied, for these samples. The sublattice magnetization H(T) obeys the one-third power law in the range 0.47<T/TC<0.92