Magneto-dielectric properties of Mg-Cu-Co ferrite ceramics: I. Densification behavior and microstructure development

Abstract

The densification, grain growth, and microstructure development of Mg-Cu-Co ferrite ceramics (MgFe1.98O4, Mg1-xCu xFe1.98O4, with x=0.10-0.30 and Mg 0.90-xCoxCu0.10Fe1.98O4, with x=0.05-0.20) were studied. The primary objective was to develop magneto-dielectric materials for miniaturization of high frequency and very-high frequency antennas. It was found that magnesium ferrite (MgFe 1.98O4) is a promising magneto-dielectric material. However, due to its poor densification, it could not be fully sintered at a temperature below 1200°C. High-temperature sintering resulted in undesirable electrical and dielectric properties, due to the formation of Fe2+ ions. The poor densification and slow grain growth rate of MgFe 1.98O4 can be considerably improved by incorporating Cu, due to the occurrence of liquid-phase sintering at a high temperature. A critical concentration of Cu was observed for Mg1-xCu xFe1.98O4, above which both densification and grain growth were maximized or saturated. The presence of Co did not have a significant influence on the densification and grain growth of the Mg-based ferrite ceramics. © 2007 The American Ceramic Society.