Complex additive systems for Mn-Zn ferrites with low power loss

摘要

Mn-Zn ferrites were prepared via an oxalate-based wet-chemical synthesis process. Nanocrystalline ferrite powders with particle size of 50 nm were sintered at 1150℃ with 500 ppm CaO and 100 ppm SiO_2 as standard additives. A fine-grained, dense microstructure with grain size of 4-5 μm was obtained. Simultaneous addition of Nb_2O_5, ZrO_2, V_2O_5, and SnO_2 results low power losses, e.g., 65 mW/cm~3 (500kHz, 50mT, 80℃) and 55 mW/cm~3 (1 MHz, 25 mT, 80℃). Loss analysis shows that eddy current and residual losses were minimized through formation of insulating grain boundary phases, which is confirmed by transmission electron microscopy. Addition of SnO_2 increases the ferrous ion concentration and affects anisotropy as reflected in permeability measurements μ(T).