Effect of Cr-Bi substitution on the structural, optical, electrical and magnetic properties of strontium hexaferrites

M-type hexagonal ferrite, SrFe12-2xCrxBixO19 (x = 0.0-0.2) was prepared using sol-gel auto combustion technique. X-ray diffraction (XRD), Fourier transform infra-red (FTIR), Raman spectroscopy, field emission scanning electron microscopy (FESEM), UV-Vis-NIR spectroscopy, vibrating sample magnetometer (VSM) and impedance analyzer were respectively used to investigate the structural, optical, electrical and magnetic properties of the synthesized materials. XRD analysis reveals the formation of single phase of M-type hexaferrite with crystallite size ranging from 33 to 42 nm. The presence of peaks at 441, 552, and 598 cm(-1) in the FTIR spectra indicate the formation of hexaferrite phase. FESEM images shows agglomerated particles having almost hexagonal shapes. The band gap of the material lies between 1.71 and 1.96 eV. The saturation magnetization and remanence enhances with increasing Cr3+-Bi3+ concentration. The dielectric constant and dielectric loss tangent decrease with increase in frequency while AC conductivity shows an increase at higher frequencies.