This work presents the estimation of cation distribution of ultrafine NixCo1−xFe2O4 nano-ferrites (x = 0, 0.25, 0.5, 0.75 and 1) from structure, magnetic and electrical investigations. “Sol gel” was the method used to synthesize Ni–Co ferrites. Ni2+-doped CoFe2O4 nanostructure has a broad range of electromagnetic applications due to its controllable magnetic and electrical properties. From XRD patterns, the formation of pure phase was obvious, and the crystallite size ranged from 9 to 12 nm. These sizes are small enough to achieve suitable signal-to-noise ratio for high-density recording media and have more opportunities for technological application, especially in medical fields. Besides, the variation of theoretical lattice parameter with x-content was in a good agreement with experimental ones. Field Emission Scanning Electron Microscope (FESEM) revealed the formation of small nanosphere particles with gradual size reduction on addition of Ni2+ ions. Energy-Dispersive X-ray analysis (EDX) confirmed the purity of prepared samples. Magnetic parameters (Ms, Mr and Hc) were determined from Vibrating Sample Magnetometer (VSM). It was found that both Ms and Hc have gradual decrease with increasing x-content. Curie temperature was determined from the variation of relative permeability with temperature and showed also a gradual decrease with addition of Ni2+ ions. Temperature dependence of both DC electrical resistivity and thermoelectric power coefficient were carried out in the temperature range 385–548 K. The resistivity showed a gradual decrease with increasing x-content. However, the negativity of thermoelectric power coefficient showed a gradual increase with addition of Ni2+ ions. Conduction mechanism was deduced for all studied samples from activation energy values. The cation distribution was proposed such that it could verify the lattice parameter and magnetization of each composition as well as the behavior of resistivity and thermoelectric power.

中文翻译：

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阳离子分布与超细Ni2+掺杂CoFe2O4的结构、磁学和电学性质的相关性

这项工作从结构、磁性和电学研究中提出了对超细 NixCo1-xFe2O4 纳米铁氧体（x = 0、0.25、0.5、0.75 和 1）的阳离子分布的估计。“溶胶凝胶”是用于合成镍钴铁氧体的方法。Ni2+ 掺杂的 CoFe2O4 纳米结构由于其可控的磁和电特性而具有广泛的电磁应用。从XRD图谱可以看出，纯相形成明显，晶粒尺寸为9～12nm。这些尺寸足够小，可以为高密度记录介质实现合适的信噪比，并有更多的技术应用机会，尤其是在医疗领域。此外，理论晶格参数随 x 含量的变化与实验结果吻合良好。场发射扫描电子显微镜 (FESEM) 揭示了在添加 Ni2+ 离子后尺寸逐渐减小的小纳米球颗粒的形成。能量色散 X 射线分析 (EDX) 证实了制备的样品的纯度。磁参数（Ms、Mr 和 Hc）由振动样品磁强计 (VSM) 确定。发现随着x含量的增加，Ms和Hc均逐渐降低。居里温度由相对磁导率随温度的变化确定，并且随着 Ni2+ 离子的加入，居里温度也逐渐降低。直流电阻率和热电功率系数的温度依赖性在 385-548 K 的温度范围内进行。电阻率随着 x 含量的增加而逐渐降低。然而，热电功率系数的负值随着Ni2+离子的加入而逐渐增大。从活化能值推导出所有研究样品的传导机制。提出了阳离子分布，以便它可以验证每种成分的晶格参数和磁化强度以及电阻率和热电功率的行为。