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<inf>1-x</inf>Al<inf>2</inf>Co<inf>x</inf>Fe<inf>4</inf>O<inf>11</inf> (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 Fe<inf>3</inf>O<inf>4</inf> phase. Magnetic parameters like saturation magnetization (M<inf>s</inf>), coercive field (H<inf>c</inf>), and remanent magnetization (M<inf>r</inf>), 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.