文摘
SrBixLaxFe12-2xO19 (0.0≤x≤0.5) hexaferrites were synthesized by sol-gel auto combustion technique. The influence of Bi and La substitutions on structural, magnetic and optical properties were investigated by X-ray diffraction (XRD), Furrier transformed infrared (FT-IR), Vibrating sample magnetometer (VSM) and Percent diffuse reflectance spectroscopy (DR %). XRD analysis confirmed the single phase formation for all the samples, the purity of the products was also confirmed by FT-IR. The specific magnetization (σ-H) curves revealed the ferromagnetic nature of the samples. The extrapolated specific saturation magnetization (σs) decreases from 63.45 emu/g to 49.84 emu/g with increasing Bi, La substitutions. Similar decrement is observed from 32.6 emu/g to 25.8 emu/g at remnant magnetization (σr). The average crystallite size varies in a range of (43.28–51.40) nm. The coercive fields are between 4682 and 5315 Oe. Magnetic anisotropy was assigned as uniaxial and calculated effective anisotropy constants (Keff) are between 5.57×105 Ergs/g and 4.03×105 Ergs/g. The observed high magnitudes of intrinsic coercivity (Hci) above 16,000 Oe confirm hard magnetic nature of the samples. The Tauc plots were used to extrapolate the direct optical energy band gap (Eg) of hexaferrites. The Eg values decreased from 1.81 to 1.68 eV with increasing Bi, La contents.