Effect of Y 2O 3 additive on the microstructure and high-frequency properties of Z-type hexaferrites

Abstract

In order to improve the high-frequency electromagnetic properties of Z-type hexaferrites such as high cut-off frequency and low dielectric constant, Y 2O 3 was introduced. The influence of Y 2O 3 additive on the phase composition, densification, microstructural and electromagnetic properties of the ceramics with composition of Ba 3(Co 0.4Zn 0.6) 2Y x Fe 24− x O 41 ( x=0−1) was investigated. The results show that as the amount of Y 2O 3 additive increased, the major phase changed to Z-phase; simultaneously, a small amount of garnet phase appeared. With increasing Y 2O 3 content, the garnet phase separated out on grain boundaries as a secondary phase restraining grain growth. When x was varied from 0 to 1, the dielectric constant decreased and the ferroelectric resonance peak shifted toward a higher frequency. Meanwhile, the initial permeability increased at first, and then decreased with further increasing x, which could be mainly attributed to the change of phase composition and sintering density. With increasing Y 2O 3 content, the minimum reflection point of the samples shifted toward a higher frequency.