The effects of Mn substitution on the crystalline phase structure, microstructure, DC resistivity, and magnetic-dielectric properties of Z-type hexaferrites

Abstract

A series of the Ba1.5Sr1.5Co2-xMnxFe23O41 (x = 0.0–0.5) hexaferrites was prepared by the conventional solid-state reaction method. The crystalline phase structure, microstructure and magneto-dielectric properties of samples were investigated. Z-type and W-type phases were detected in hexaferrites sintered at 1200 °C. Mn substitution can reduce the content of the second phase, changes the ion occupancy, magnetic moment, and electron hopping in hexaferrite. Therefore, the magnetic, DC resistivity, and dielectric properties were altered, and the losses were successfully reduced in the substituted samples. Particularly, the Ba1.5Sr1.5Co1.8Mn0.2Fe23O41 hexaferrite has a more homogeneous crystal phase; its μi is 18.5, fr exceeds 1 GHz, and the Snoek’s constant reaches 18.55 GHz. At the same time, this hexaferrite were characterized by a relatively large magnetic quality factor and low dielectric losses (tanδε<0.05 below 500 MHz). This Z-type hexaferrite has excellent high-frequency magneto-dielectric properties and holds a potential for use in miniature antennas.