Investigation of Structural and Magnetic Properties on Mg1−xZnxFe2−xAlxO4 (0.0 ≤ x ≤ 0.8) Nanoparticles.

A mixed spinel ferrite nanoparticle, Mg_1−xZn_xFe_2−xAl_xO₄ NPs (0.0 ≤ x ≤ 0.8), were synthesized effectively by co-precipitation method and sintered at 600 °C for 10 h. The structural and magnetic properties of the products were studied through X-ray powder diffraction (XRD), scanning electron microscopy, transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer. The cubic spinel phase was confirmed by XRDs with particle size between 24.5 and 40.2 nm. The lattice parameters for the products are increased with increasing the Zn²⁺ and Al³⁺ ratio due to the successfully integrated into the cubic system without changing the original structure. Although it was observed from the cation distributions, that the cubic phase is was an inverse spinel, wherein which the Fe³⁺ and Mg²⁺ ions occupied both the tetrahedral A and octahedral B- sites, the Zn²⁺ ions preferred to occupy the A- sites and Al³⁺ occupy preferred the B -sites. The morphology of the nanoparticles NPs detailed was using TEM, HR-TEM, and SAED in selected area confirmed the particle size and crystalline spinel structure. Magnetization results at room temperature presents a narrow hysteresis loop for all ratios, which is specific of the soft magnetic materials. Also, we noticed that the increase in the magnetization with increasing the ratio of Zn²⁺ and Al³⁺ consistent with the enhancement of crystallinity. Moreover, we found that the saturation magnetization, coercively and remanent for Mg_1−xZn_xFe_2−xAl_xO₄ where x = 0.6 sample is the highest, indicating the potential of Zn and Al substitution in enhancing the magnetic properties of magnesium ferrite. According to AC magnetic susceptibility measurements, the nanoparticles exhibit superparamagnetic/spin glassy behaviour with a very strong inter-nanoparticles interaction. Additionally, AC susceptibility measurements indicated a relative sensitivity of samples to the variation of applied frequency, which is an important result for the applications in hyperthermia based therapy. This is the first study in which both Zn²⁺ and Al³⁺ ions with varying concentration were tried to substitute into MgFe₂O₄ simultaneously and their effects on magnetic properties of MgFe₂O₄ was investigated. [ABSTRACT FROM AUTHOR]