MÖSSBAUER SPECTROSCOPY OF Ni-FERRITE AND NON-STOICHIOMETRIC Ni-Zn FERRITES

Abstract

The Miissbauer absorption spectra of Ni-ferrite and non-stoichiometric Ni-Zn ferrites in the compositions (0.3 Ni0-0.7 Z~O)I-~(F~ZO,)I- ~, x = 0, x - 0.02, were obtained at room temperature and 77 K. For Ni-ferrite, the hyperfine fields associated to the iron nuclei at the octahedral and tetrahedral sites were resolved, at both temperatures. The relative intensities of these spectra presented a peculiar behavior in temperature. In the case of non-stoichiometric Ni-Zn ferrites, a broadening in the lines did not allow the hyperfine fields to be resolved. However, the Mossbauer spectra presented different features, showing that even for small deviations from stoichiometry, the structural changes are important.