Abstract In this work, structural and magnetic properties of Ni0.5MgxZn0.5-xFe2O4 (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5) nanocrystalline ferrites synthesized via the co-precipitation method are reported. The ferrites are found to be at the nano-scale with sizes below 30 nm and seem porous in their general appearance. The structural properties were investigated using X-ray and Infrared (IR) spectra. X-ray Diffraction (XRD) patterns have been refined using the Rietveld method to find the lattice parameters. It was found that all these ferrites are a single-phase cubic spinel related structure belonging to the Fd-3m space group. Further, the positions, occupancy and Wyckoff's cationic position of the ions, in addition the lattice constant (a), the crystallite size (D) and the micro-strain of the composites have been analyzed and found to be affected by the variation of the Mg2+ ions concentration. The Vibrating Sample Magnetometer (VSM) technique showed that these nanoparticles are superparamagnetic with approximately impermanent magnetization of relatively high values. It was also found that the magnetization values of the Ni0.5MgxZn0.5-xFe2O4 (0.0 ≤ x ≤ 0.5) system increase with the existence of the Mg2+ and the Zn2+ contents together (at x = 0.1, 0.2, 0.3, 0.4) due to the increase in the super exchange interaction happening between the Fe3+ and the Ni2+ ions resulting from the occupation of the Mg2+ and the Zn2+ ions (nonmagnetic) to exclusively the A-sites as indicated by the Rietveld's structural analysis. These composites are expected to be promising for biomedical applications due to their superparamagnetic property below 30 nm.

中文翻译：

---

Ni0.5MgxZn0.5-xFe2O4(0.0≤x≤0.5)纳米晶尖晶石铁氧体的合成及磁性能

摘要 在这项工作中，报道了通过共沉淀法合成的 Ni0.5MgxZn0.5-xFe2O4 (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5) 纳米晶铁氧体的结构和磁性能。发现铁氧体为纳米级，尺寸低于 30 nm，并且在它们的总体外观上似乎是多孔的。使用 X 射线和红外 (IR) 光谱研究了结构特性。X 射线衍射 (XRD) 图案已使用 Rietveld 方法进行细化以找到晶格参数。发现所有这些铁氧体都是属于 Fd-3m 空间群的单相立方尖晶石结构。此外，离子的位置、占有率和威科夫阳离子位置，以及晶格常数 (a)，分析了复合材料的微晶尺寸 (D) 和微应变，发现它们受 Mg2+ 离子浓度变化的影响。振动样品磁力计 (VSM) 技术表明，这些纳米颗粒是超顺磁性的，具有相对较高的近似非永久性磁化强度。还发现 Ni0.5MgxZn0.5-xFe2O4 (0.0 ≤ x ≤ 0.5) 系统的磁化值随着 Mg2+ 和 Zn2+ 含量的存在而增加（在 x = 0.1、0.2、0.3、0.4） Rietveld 的结构分析表明，由于 Mg2+ 和 Zn2+ 离子（非磁性）占据 A 位，Fe3+ 和 Ni2+ 离子之间发生的超级交换相互作用增加。