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

The polycrystalline Ni0.56Cu0.10Zn0.34Fe2−xO4−3/2x (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 Bs and the coercivity Hc. More importantly, based on the Néel molecular field theory, for the spinel ferrites which do not only contain Fe3+ but also some other multiple magnetic ions (Ni2+ and Cu2+), the molecular field coefficients ωaa, ωbb and ωab=ωba are calculated by non-linear fitting method, and the Curie temperature Tc formula has been modified. With the increase of Fe-deficiency content, the values of ωaa and ωbb increase gradually, however, the value of ωab=ωba 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.