Reduced A–B super exchange interaction in Sm³⁺–Gd³⁺-doped Mn–Zn ferrites due to high energy gamma irradiation

Abstract

We report the effect of gamma irradiation on structural and magnetic properties of ${\text{Mn}}^{2 + }_{0.4} {\text{Zn}}^{2 + }_{0.6} {\text{Sm}}^{3 + }_{x} {\text{Gd}}^{3 + }_{y} {\text{Fe}}^{3 + }_{2 - (x + y)} {\text{O}}_{4}$ (where x = y = 0.01, 0.02, 0.03, 0.04 and 0.05) ceramics prepared by self-propagating high-temperature synthesis method using glucose and urea as fuels. The synthesized samples are characterized through X-ray diffractometer (XRD) and vibration sample magnetometer at room temperature before and after gamma irradiation. The XRD patterns of before irradiation samples reveal the formation of polycrystalline, mixed spinel cubic structure. The mixed (impurity) phases are identified as Fe₂O₃, SmFeO₃ and GdFeO₃, and the amount of these residual phases is comparatively less after gamma irradiation. Lattice parameter is found to be increasing with increasing Sm³⁺ and Gd³⁺ concentration is observed after gamma irradiation. This is due to the irradiation of ionizing gamma radiation with the material which gives rise to the production of lattice defect and then the displacing of atoms from their equilibrium position. The magnetic properties reveal that saturation magnetization (M_s), remnant (M_r), remnant ration (M_r/M_s), coercivity (H_c), magneton number (η_B), anisotropy constant (K) have been decreasing with increasing Sm³⁺ and Gd³⁺ concentration before and after gamma irradiation. This is due to breaking of ferrimagnetic ordering, surface state pinning and cation inversion of the materials. Hence, our results propose the good radiation stability of the samples when compared to reported material stability in the literature.