Relationship between Curie temperature and Brillouin function characteristics of NiCuZn ferrites

Abstract

Based on Néel's two-sublattice collinear model, the relationship between Curie temperature Tc and temperature characteristics of Brillouin function for NiCuZn ferrites has been studied by nonlinear fitting calculation method. According to the tetrahedral A sites and the octahedral B sites of spinel structure model which do not only contain Fe3+ but also some other multiple magnetic ions (Ni2+and Cu2+), molecular-field coefficients ωaa, ωbb, and ωab = ωba have been calculated; furthermore, the ferrimagnetism and paramagnetism Curie temperature Tc calculation formula has been modified, respectively. The magnetic moment versus temperature T (below the Curie temperature Tc) and the reciprocal of paramagnetism magnetic susceptibility 1/χm versus temperature T (beyond the Curie temperature Tc) have been investigated, respectively. The values of the calculated ferrimagnetism Curie temperature are very close to the values of the testing Curie temperature, and with the same zinc content t, the values of paramagnetic Curie point are all bigger than that of ferrimagnetism Curie point. With regard to different zinc contents, the fitting results are coincided well with the experimental data. With the increasing of zinc content, ωaa increases constantly. However, ωab = ωba shows an opposite trend and ωbb is invariant.