Magnetic and optical characterizations of Dy-Eu co-substituted Mn0.5Zn0.5Fe2O4 nanospinel ferrites

Abstract

In this study, Mn0.5Zn0.5DyxEuxFe2–2xO4 (x ≤ 0.1) nanospinel ferrites (DyEu→MnZn (x ≤ 0.1) NSFs) were synthesized via ultrasonication method. The microstructure of samples was characterized by XRD, which confirmed the cubic spinel phase without any impurity and the nanostructure of all samples. TEM and SEM also proved the samples' morphology and chemical composition along with EDX. Diffuse reflectance (DR) spectra investigations were performed on samples. Direct optical energy band gaps (Eg) were studied by using the Tauc approximation and were found between 2.44 and 2.56 eV. The impact of Eu3+-Dy3+ ions inclusion on the magnetic properties of DyEu→MnZn (x ≤ 0.1) NSFs was also investigated. The magnetic M-H hysteresis loops showed non-hysteretic behavior at 300 K, suggesting the superparamagnetic (SPM) behavior. In contrast, finite values of coercivity and remanence are observed at lower temperatures (T) (10 K), revealing the transition to ferromagnetic (FM) behavior at low Ts. As the concentration of Eu3+-Dy3+ ions increases, it is noticed that the saturation magnetization (Ms) decreases, whereas the coercivity (Hc) increases. The curves of T-dependent magnetization M(T) under FC and ZFC modes confirmed the SPM-FM phase transition with decreasing the T. It is found that the blocking temperature (TB) is slightly decreasing with increasing the Eu3+-Dy3+ ions content. All samples displayed spin-glass-like behavior at low Ts, which indicates strong interactions among the magnetic moments.