Effect of rare earth substitution on magnetic properties of strontium hexaferrite prepared by Pechini method

This study presents a comprehensive investigation into the impact of substituting rare earth elements on the magnetic properties of strontium hexaferrite. The samples, synthesized by the sol-gel Pechini method, followed the formula Sr _1-xRe _xFe ₁₂O ₁₉ with Re = Gd, Sm, Nd, Pr, and La, for 0.025 ≤ x ≤ 0.100. The findings revealed that Re substitution promotes a considerable increment of the coercive field. However, the magnetic yield dropped with increasing the Re content. Therefore, the higher coercivity field, largest magnetization and maximum energy product ( BH _max ) were reached for samples with x = 0.025. This tendency was consistent across all rare earth-substituted samples although the hexaferrite substituted with samarium and praseodymium showed the strongest hard-magnetic properties. This behavior has been attributed to a reduction of the interaction field due to the emergence of a monodomain structure, and to the limited solubility of rare earth elements within the structure of strontium hexaferrite.