Intrinsic magnetic properties and microstructures of Bi-substituted M-type SrBaLa hexaferrite powders

In this study, M-type hexagonal Sr0.4Ba0.3La0.3Fe12-xBixO19 (0 ≤ x ≤ 0.4) magnetic powders were synthesized by the solid statereaction method. The phase composition and magnetic properties of the magnetic powders were characterized by an X-raydiffractometer (XRD) and a vibrating sample magnetometer (VSM), respectively. The results of XRD show that all samplesexhibit a well-defined M-type hexaferrite phase when Bi content (x) ≤ 0.2, while for the magnetic powder with x ≥ 0.3, the XRDpatterns show the M-type strontium hexaferrite structure and two peaks of BiFeO3 as a second phase are observed. Thesaturation magnetization (Ms) and remanent magnetization (Mr) first increase with Bi content (x) from 0 to 0.1, and thendecrease when Bi content (x) ≥ 0.1. The coercivity (Hc) decreases quickly with Bi content (x) from 0 to 0.1, then begins toincrease with Bi content (x) from 0.1 to 0.3, and when x > 0.3 the coercivity (Hc) decreases significantly.