Effect of Bi ₂ O ₃ on Impurity Ion Distribution and Electrical Resistivity of Li‐Zn Ferrites

Abstract

Preventing the incorporation of impurities in Li‐Zn ferrite grains during sintering is essential for production of ceramics with reproducible magnetic and electrical properties. Li‐Zn ferrites of composition Li 0.3 Zn 0.4 Mn 0.05 Fe 2.25 O 4 were prepared with Bi 2 O 3 and borosilicate sintering additives. The distribution of impurity ions in the sintered ferrites was investigated using transmission electron microscopy (TEM) coupled with energy dispersive spectroscopy (EDS). Ceramics prepared with Bi 2 O 3 contained Si, Ca, and S impurities, located at grain boundaries and triple point regions. The low viscosity and good wetting properties of the Bi 2 O 3 and to a lesser extent the borosilicate liquid phase allowed impurities to be selectively removed from the growing ferrite phase during sintering, thus improving sample resistivities.