Effect of Al 3+ and Y 3+ Substitutionon the Structural, Mossbauer and Magnetic Properties of Ni-Zn-Co Spinel Ferrites

Co 0.2 Ni 0.4 Zn 0.4 AlbYaFe 2-a-b O 4 (0≤a,b≤0.2)spinel ferrites were prepared using a sol-gel auto-combustion approach to systematically investigate the impact of individual and simultaneous Al 3+ Y 3+ doping on their crystallographic, local hyperfine, and magnetic properties. XRD is consistent with the preservation of a single-phase spinel structure across all samples; however, Al 3+ substitution drives lattice contraction, while Y 3+ induces lattice expansion and hinders crystallite growth at elevated doping concentrations. Mssbauer spectra reveal that Y 3+ incorporation predominantly intensifies local magnetic disorder and relaxation phenomena, whereas Al 3+ exerts a relatively limited influence on the hyperfine parameters and may induce a certain degree of cation redistribution. Magnetically, all ferrites display soft ferrimagnetism. Doping attenuates both saturation magnetization (Ms) and coercivity (Hc), yielding a maximized magnetic softening in the co-doped configurations. Ultimately, these findings suggest that incorporating varying-sized trivalent ions can effectively tailor the magnetic response of Ni-Zn-Co ferrites by modulating local structural distortions and exchange interactions.