Brillouin function for thermomagnetization characteristics of LiZnMn ferrites

The polycrystalline Li_{0.499−0.5 x} Zn _x Co_0.002Mn_0.06Fe_{2.439−0.5 x} O₄ ( x   =  0.1–0.4) ferrites have been fabricated by solid-state method. According to the Brillouin function for ferrites, the temperature characteristics of magnetization of LiZnMn ferrites have been investigated by nonlinear fitting method. For the spinel structure consisted of tetrahedral A sub-lattice and antiparallel octahedral B sub-lattice simultaneously occupied by multiple magnetic ions (Co²⁺, Mn³⁺, and Fe³⁺), respectively, based on the two-sublattice molecular-field theory, the intra-sublattice molecular-field coefficients λ _AA , λ _BB , and the inter-sublattice molecular-field coefficients λ _AB   =   λ _BA have been calculated. Furthermore, both ferrimagnetism and paramagnetism thermomagnetic characteristics have been investigated. In addition, the Curie temperature T _c calculation formula for ferrimagnetism and paramagnetism have been modified, respectively. The results show that the calculated values are well coincided with the experiment results. Along with increasing of the zinc content, the absolute value of λ _BB increases constantly, however, these of λ _AA and λ _AB   =   λ _BA show an opposite trend, meanwhile, the strength of superexchange interaction mainly depends on λ _AB   =   λ _BA . (paper)