Correlation between the microstructure and permeability stability of ferrite materials

Permeability stability is very important for ferrite materials used in modern electronic devices. In this study, different contents of Bi2O3-B2O3-SiO2-ZnO (BBSZ) glass were added to NiCuZn ferrite materials to obtain samples with different average grain sizes and grain boundary thicknesses. On the premise of obtaining the same permeability, this study determined that ferrite sample with a large average grain size and thick grain boundary width presented better permeability stability characteristics, including frequency stability, temperature stability, and DC-bias-superposition stability, than the sample with a small average grain size and thin grain boundary. This study subsequently established a model and theoretically demonstrated why the sample with a larger average grain size and thicker grain boundary width possessed superior permeability stability characteristics. This investigation provides a good guide for developing superior stable ferrite materials by improving microstructure characteristics.