Research on La3+–Co2+-substituted strontium ferrite magnets for high intrinsic coercive force

M-type strontium ferrites with substitution of Sr2+ by rare-earth La3+, and a little amount of Fe3+ by Co2+ according to the formula Sr1−xLaxFe12−xCoxO19, are prepared by the ceramic process. Effects of the substituted amount of La3+ and Co2+ on structure and magnetic properties of Sr1−xLaxFe12−xCoxO19 compounds have systematically been investigated by X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and B–H hysteresis curve measurements. In our results, the suitable amount of La3+–Co2+ substitution may remarkably increase saturation magnetization. Intrinsic coercive force (Hcj) of Sr ferrite magnets is evidently increased without significant decrease in residual flux density (Br) by La3+–Co2+ substitution.