Elucidation of phase evolution, microstructural, Mössbauer and magnetic properties of Co2+[sbnd]Al3+ doped M-type Ba[sbnd]Sr hexaferrites synthesized by a ceramic method

Abstract

M-type hexagonal ferrites with chemical composition Ba0.5Sr0.5CoxAlxFe12−2xO19 (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) have been synthesized by a standard ceramic method. The structural and parameters associated with magnetic properties have been investigated as a function of Co2+ and Al3+ ions substitution in Ba0.5Sr0.5CoxAlxFe12−2xO19 ferrites at room temperature. X-ray diffraction and Fourier transform infrared spectroscopy were used to study the structure of the compositions, and grain morphology was evaluated with scanned electron micrographs (SEM). The Mössbauer studies were performed to investigate the site occupancy and hyperfine interactions in the compositions. The vibrating sample magnetometer was used to record hysteresis loops and magnetic parameters were calculated from hysteresis curves. XRD and FTIR analysis depict the formation of M-type and Spinel phases of the synthesized compositions. SEM images of all compositions show micrometer size structure in the compositions and variation of observed porosity in SEM with substitution is in agreement with calculated porosity from XRD and bulk density. The substitution of Co2+ and Al3+ ions results in reduction of coercivity and saturation magnetization by 76.76% and 38.40% respectively from x = 0.0 to 1.0. The remanent magnetization also observes reduction with substitution. The compositions have good scope for recording and microwave absorber applications.