Vol. 7, Issue 1, Part A (2025)

Three polycrystalline specimens of spinel ferrite series, MgAl_xCr_xFe_2-2xO₄ where x=0.1,0.5 and 0.7, have been synthesized by conventional double sintering ceramic route. The samples were further subjected to mechanical milling for 3hand 6h durations. The combined effect of Al3+-Cr³⁺ions co-substitution for Fe⁺³ ions and high energy ball milling on structural, micro-structural, and magnetic properties have been investigated. Rietveld refinements of X-ray powder diffraction profiles revealed a monophasic fcc spinel structure. The values of lattice constant, X-ray density, average crystallite size, saturation magnetization, remanence magnetization, coercivity, and magneton number are found to decrease with increasing Al-Cr concentration (x) in a system. On milling the samples for 6 h, lattice constant, effective surface area, and coercivity are found to increase while average crystallite size, particle size, saturation magnetization, remanence magnetization, and magneton number are found to decrease as compared to the samples milled for 3h duration. The cation distributions suggest that Al³⁺-ions have a preference for the A-site while Cr³⁺-ions have a strong preference for the B-site. The observed variation in structural, micro-structural, and magnetic parameters has been explained in the light of cationic substitution and mechanical milling-induced effects.