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

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 degrees C with 500 ppm CaO and 100 ppm SiO2 as standard additives. A fine-grained, dense microstructure with grain size of 4-5 mu m was obtained. Simultaneous addition of Nb2O5, ZrO2, V2O5, and SnO2 results low power losses, e. g., 65 mW/cm(3) (500 kHz, 50 mT, 80 degrees C) and 55 mW/cm(3) (1 MHz, 25 mT, 80 degrees C). 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 SnO2 increases the ferrous ion concentration and affects anisotropy as reflected in permeability measurements mu(T). (C) 2015 AIP Publishing LLC.