Influence of Sm³⁺ substitution on the structural, magnetic, and dielectric properties of SrFe12O19 hexaferrites

Abstract

The sol-gel auto-combustion method has been used to prepared M-type Sr_1−xSm_xFe₁₂O₁₉ hexagonal ferrite nanoparticles with various compositions x = 0.0, 0.02, 0.04, 0.06, 0.08 and 0.1 respectively. The samples were sintered for 4 h at 1200 °C for the reaction to occur and investigate the effects of Sm³⁺ substitution on the host material’s structural, magnetic, and dielectric properties. The properties of these were investigated using XRD, FESEM, FTIR, magnetic, and impedance analysis. The confirmation of the formation of the crystalline M-type has been carried out by XRD patterns, which were identified as pure hexagonal with space group P6₃/mmc (No. 194). The morphology observed under FESEM was a speckle-like morphology in the nanoscale. FTIR analysis confirmed the synthesis of hexaferrite, where stretching bands of oxygen atoms and metal ions (M–O), in this case the Fe–O bond is observed in the range 413–421 cm^− 1 and 586–593 cm^− 1. The saturation magnetization decreases with increasing concentrations and is low at x = 0.10. The concentration of Sm³⁺ increases the coercivity. The dielectric analysis showed that the sample has a frequency-dependent behavior, with the highest dielectric constant value of the synthesized sample and a low value for dielectric loss. The polarization and conduction mechanisms were explained by Koop’s theory, the Maxwell-Wagner model, and the Verwey hopping model.