M?ssbauer Effect Study of Copper Containing Nickel-Aluminate Ferrite

A series of spinel ferrite system Ni1-xCuxFeAlO4 with (0.0x1.0) were prepared, checked by X-ray, and studied with 57Fe M?ssbauer effect spectroscopy in the 77–470 K temperature range. Characteristic spectra of paramagnetic, magnetic, and electronic types for the different compositions have been observed. Cation distribution obtained from spectral analysis revealed an inverse spinel system. Hyperfine parameters at 77 K were found to be temperature and concentration independent. At 293 K the hyperfine field decreases with increasing Cu concentration. Nèel point TN obtained were found to decrease linearly with the compositional parameter x. Debye temperature D of this ferrite system increases with increasing Cu content. The temperature dependence of the sublattice magnetization s(T) obeys a 1/3 power law in the 0.5