Magneto-optical properties BaBixLaxFe12−2xO19 (0.0≤x≤0.5) hexaferrites

Abstract

BaBixLaxFe(12−2x)O19 (0.0≤x≤0.5) hexaferrites were synthesized by solid state synthesis route and the effects of Bi, La substitutions on structural, magnetic and optical properties were investigated. X-ray powder diffraction, Scanning electron microscopy, Vibrating sample magnetometer, and Percent diffuse reflectance spectroscopy were used to study the physical properties. Room temperature specific magnetization (M–H) curves revealed the ferromagnetic nature of all products. The increasing Bi, La compositions increased the magnetic properties at different magnitudes with respect to undoped BaFe12O19 sample. The maximum values of remnant specific magnetization (Mr=30.3emu/g), extrapolated specific saturation magnetization (Ms=62.12emu/g), and magneton number (nB=16.27) were recorded from BaBi0.2La0.2Fe11.4O19 hexaferrite. The average crystallite size varies in a range of (37.35–51.36)nm. The coercive field (Hc) of undoped hexaferrites is 1180Oe and increased to maximum 2320Oe belonging to BaBi0.4La0.4Fe11.2O19. Magnetic anisotropy was confirmed as uniaxial and calculated effective anisotropy constants (Keff) are between 4.27×105Ergs/g and 5.05×105Ergs/g. The high magnitudes of magnetocrystalline anisotropy (Ha) above than 16,200Oe revealed that all samples are magnetically hard materials. The Tauc plots were drawn to extrapolate the direct optical energy band gap (Eg) of hexaferrites. The Eg values decreased from 1.76eV to 1.47eV with increasing Bi, La compositions.