Effect of composition and temperature on the magnetic properties of BaBixLaxFe(12-2x) O19 (0.0 ≤ x ≤ 0.2) hexaferrites

Bi-La-substituted M-type barium hexaferrites, BaBixLaxFe(12-2x)O19 (0.0 <= x <= 0.2), were prepared by the standard solid-state reaction method. The effect of temperature and concentration on the structural and magnetic properties of BaBixLaxFe(12-2x) O-19 hexaferrite powders has been comprehensively investigated. XRD analysis confirms the formation of M-type hexagonal crystal structure with P6(3)/mmc space group. The average crystallite size of the powders was determined using Scherrer's formula (in the range of 66-77 nm.). Lattice parameters were found to increase with the increase in Bi-La substitution. Magnetic properties were enhanced by substitution. Magnetic hysteresis loops were analysed using a 'Law of Approach to Saturation' method. It was obtained the saturation magnetization value close to the bulk value. Bi-La substitution gives rise to increase of saturation magnetization, coercive field, and effective magnetic anisotropy constant for both 10 and 300 K. It is observed from FMR measurements that resonance field increases with the concentration. The broad FMR linewidth of almost 2.5 kOe indicates the existence of the particles with randomly distributed anisotropy axis. The enhanced magnetic properties make these powders a good candidate for potential applications in permanent magnets at low cost and microwave absorption devices.