Enhanced magnetic properties of x SrFe₁₂O₁₉/(1  −   x )CoFe₂O₄ composites

xSrFe₁₂O₁₉/(1  −   x )CoFe₂O₄ (0  ⩽   x   ⩽  1.0) composites with about 2 µ m average particle size were prepared by a conventional solid-state route. Results show that the xSrFe₁₂O₁₉/(1  −   x )CoFe₂O₄ composites exhibit a typical single-phase magnetic behavior, suggesting the existence of an exchange-coupling effect. The saturation magnetization ( M _s) of the composites sintered at 1230 °C increases from 49.05 to 64.84 A · m² · kg⁻¹ with the increase of CoFe₂O₄ content. Compared with single-phase CoFe₂O₄, the coercivity ( H _c) of the composites is enhanced markedly from 10.47 to 116.66 kA · m⁻¹. The enhancement of magnetic properties is ascribed to the high coercivity of SrFe₁₂O₁₉, high saturation magnetization ( M _s) of CoFe₂O₄ and the exchange-coupling effect between SrFe₁₂O₁₉ and CoFe₂O₄ ferrites. (paper)