Lattice strain mediated dielectric and magnetic properties in La doped barium hexaferrite

The lanthanum (La³⁺) doped M-type barium hexaferrite (Ba_1−xLa_xFe₁₂O₁₉) with x = 0.0, 0.05, 0.10, 0.15, and 0.20 have been prepared by the sol-gel technique. The Rietveld refinement of X-ray diffraction (XRD) patterns reveals the crystallization of all the samples to hexagonal crystal symmetry with P6₃/mmc space group. Investigation of Raman spectra strongly supports the XRD pattern analysis. The average grain (particle) size is found to be above 300 nm. Both the saturation magnetization and magnetocrystalline anisotropy have been estimated by employing the "Law of Approach (LA) to Saturation magnetization". Both the above parameters are found to be maximum for 10% La doped BaFe₁₂O₁₉. It could be due to the lattice strain mediated magnetism in barium hexaferrite. However, these magnetic parameters decrease with the increase in La doping beyond 10% (>x = 0.10) in barium hexaferrite. The dielectric permittivity gradually increases with the La concentration in the BHF. A correlation between dielectric constant with the lattice strain has been reported in La³⁺ doped barium hexaferrite.