Investigate the effect of the synthesis method on the magnetic dynamic properties of SrAl4Fe8O19 hexaferrite

Abstract

M-type SrAl4Fe8O19 hexaferrite was synthesized through three different synthesis methods, i.e., solid-state, co-precipitation, and sol–gel auto-combustion, to study the effect of synthesis on the structural and magnetic properties. X-ray diffraction (XRD), Rietveld refinement, high-resolution scanning electron microscope, and SQUID-magnetic property measurement system (MPMS) magnetometer were performed. The structural analysis demonstrated the formation of magnetoplumbite structure by these three synthesis methods. The variation in bond length and bond angle was also observed due to the synthesis methods, which affected the super-exchange interaction of the system. The solid-state method produced larger grains and more significant saturation magnetization i.e., 4.03 µm and 43.16 emu/gm, respectively, than the co-precipitate and sol–gel auto combustion methods. Magnetization–temperature (M−T) measurement revealed that the solid-state synthesized sample showed a higher blocking temperature than the rest. Magnetic susceptibility (χ) was performed with temperature dependence on different frequencies to demonstrate the magnetic dynamic properties of the SrAl4Fe8O19 hexaferrite. AC susceptibility results showed very strong magnetic interaction between particles leading to spin glass action at very low temperatures. The Neel–Arrhenius (N-A) & Vogel-Fulcher (V-F) models were used to determine the jump attempt time (τ0) and E0/KB (energy barrier or activation energy and Boltzmann constant) through AC susceptibility of magnetic particles. The τ0 and E0/KB were observed at about 2.84 × 10-11 sec and 871.31, respectively, for the solid-state synthesized sample by the V-F model.