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

Abstract BaBi x La x Y x Fe 12−3 x O 19 (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 42.35–49.90 nm. Room temperature (RT) specific magnetization ( σ – H ) data revealed the strong ferromagnetic nature of hexaferrite with remanant specific magnetization ( σ r ) in the range of 29.9–34.6 Am 2 /kg and extrapolated specific saturation magnetization ( σ s ) in the range 53.69–67.42 Am 2 /kg. The maximum coercive field ( H c ) of 3.812×10 5  A/m (belongs to BaFe 12 O 19 ) decreases to minimum 2.177×10 5  A/m with increasing ion substitution. Magnetic anisotropy was confirmed as uniaxial and effective anisotropy constant ( K eff ) takes values between 2.532×10 5  J/m 3 and 3.105×10 5  J/m 3 . The anisotropy field ( H a ) around 1.6 T revealed that all samples are magnetically hard materials. The Tauc graphs were plotted to estimate the direct optical energy band gap ( E g ) of hexaferrite. The E g values decreased from 1.88 eV to 1.69 eV with increasing Bi, La, Y compositions.