Effects of SnO2 addition on the microstructure and magnetic properties of NiZn ferrites

The microstructure and magnetic properties of SnO2-doped NiZn ferrites prepared by a solid-state reaction method have been investigated. Due to its low melting point (∼1127 °C), moderate SnO2 enhanced mass transfer and sintering by forming liquid phase, which accelerated the grain growth. However, excessive SnO2 producing much of liquid phase retarded mass transfer and sintering, leading to a decrease in grain size. The diffraction intensity of the samples doped with SnO2 addition was stronger than that of the sample without addition. The lattice constant initially decreased up to a content of 0.10 wt% and showed an increase at higher content up to 0.50 wt%. The initial permeability (μi) initially increased up to a content of 0.15 wt% and showed a decrease at higher content up to 0.50 wt%; however, losses (PL) measured at 50 kHz and 150 mT changed contrarily. Both saturation induction (BS) and Curie temperature (TC) decreased gradually with increasing SnO2. Finally, the sample doped with 0.10-0.15 wt% SnO2 showed the higher permeability and lower losses.