Effects of Fe-deficiency on magnetic properties and Brillouin function characteristics for NiCuZn ferrites.

The polycrystalline Ni 0.56 Cu 0.10 Zn 0.34 Fe 2− x O 4−3/2 x ( x =0.00~0.14) ferrites have been prepared by conventional oxide ceramics process. The effects of Fe-deficiency content on magnetic properties and Brillouin function characteristics for NiCuZn ferrites have been investigated in details. With the increase of Fe-deficiency content, the opposite variation trend are observed for the saturation magntic induction B s and the coercivity H c . More importantly, based on the Néel molecular field theory, for the spinel ferrites which do not only contain Fe 3+ but also some other multiple magnetic ions (Ni 2+ and Cu 2+ ), the molecular field coefficients ω aa , ω bb and ω ab= ω ba are calculated by non-linear fitting method, and the Curie temperature T c formula has been modified. With the increase of Fe-deficiency content, the values of ω aa and ω bb increase gradually, however, the value of ω ab = ω ba has a contrary trend which results in the decrease of the Curie temperature. In addition, the fitting Curie temperatures values are coincided well with the Curie temperatures calculated by the modified formula. [ABSTRACT FROM AUTHOR]