Synthesis, characterization and magneto optical properties of BaBixLaxYxFe12−3xO19 (0.0≤x≤0.33) hexaferrites

Abstract

BaBixLaxYxFe12−3xO19 (0.0≤x≤0.33) hexaferrites were synthesized by sol–gel autocombustion method and the effects of Bi, La, Y substitutions on structural, magneto-optical properties of barium hexaferrite were investigated. X-ray diffraction (XRD), Scanning electron microscopy (SEM), Vibrating sample magnetometer (VSM), and Percent diffuse reflectance spectroscopy (DR %), were used to study the physical properties. XRD peaks showed pure single phase of hexagonal ferrites and the average crystallite size varies in a range of 42.35–49.90nm. Room temperature (RT) specific magnetization (σ–H) data revealed the strong ferromagnetic nature of hexaferrite with remanant specific magnetization (σr) in the range of 29.9–34.6Am2/kg and extrapolated specific saturation magnetization (σs) in the range 53.69–67.42Am2/kg. The maximum coercive field (Hc) of 3.812×105A/m (belongs to BaFe12O19) decreases to minimum 2.177×105A/m with increasing ion substitution. Magnetic anisotropy was confirmed as uniaxial and effective anisotropy constant (Keff) takes values between 2.532×105J/m3 and 3.105×105J/m3. The anisotropy field (Ha) around 1.6T revealed that all samples are magnetically hard materials. The Tauc graphs were plotted to estimate the direct optical energy band gap (Eg) of hexaferrite. The Eg values decreased from 1.88eV to 1.69eV with increasing Bi, La, Y compositions.