Studying the structural, magnetic, and dielectric properties of cobalt-substituted R- type hexaferrites

A series of Co²⁺ substituted R-type hexagonal ferrites was synthesized using heat treatment method with composition Sr_1-xAl₂Co_xFe₄O₁₁ (x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5). The obtained precursors were heated at 950 ºC for 3 h and then characterized using various instrumental techniques. The XRD pattern of all the samples depicts the R-phase as a major phase with an additional Fe₃O₄ phase. Magnetic parameters like saturation magnetization (M_s), coercive field (H_c), and remanent magnetization (M_r), were estimated from hysteresis loops of the samples. Magnetic analysis revealed that prepared ferrite samples possess a multi-domain nature that is randomly oriented. The non-linear variation in magnetic parameters was observed with the increase in cobalt doping content. The dielectric constant with cobalt substitution decreases with respect to the pristine sample.