Synthesis and structural and magnetic properties of Sr_1-yPr_yFe_12-xCo_xO₁₉ nanocomposites prepared via auto combustion technique

Sr_1-yPr_yFe_12-xCo_xO₁₉ (x= 0.0- 1.5 and y= 0.1- 0.3) polycrystalline samples were prepared via auto combustion method and analyzed with respect to their structural and magnetic characteristics. The possibility of simultaneous substitution of Fe³⁺ by Co²⁺ was verified for low substitution degrees. At higher substitution of Co²⁺, a secondary soft magnetic phase CoFe₂O₄ is observed. The room temperature magnetic parameters derived from hysteresis loops showed that the saturation magnetization of Sr_1-yPr_yFe_12-xCo_xO₁₉ increased with the increase in cobalt content, and a concomitant reduction in coercivity values is controlled by substituting Pr³⁺ for Sr²⁺. Mr value increases with increasing Co²⁺ content indicating the presence of an exchange coupling between magnetic hard and soft phases of the composite. The highest magnetization 61.17emu/g and coercivity Hc 3.98 kOe is observed in y= 0.1, x= 1 content. The coercivity observed is about
11% higher than pure SrFe₁₂O₁₉. Therefore, the substitution of Pr³⁺ and Co²⁺ in SrFe₁₂O₁₉ can bring magnetization and coercivity enhancement, which is useful for the high-temperature magnetic application.