A series of chemical sample with formulae Ni_0.2Mg_0.2Co_0.6Fe_2−xCr_xO₄ (0.00 ≤ x ≤ 0.1; step 0.025) were prepared by sol–gel automatic combustion at 950 °C. X-ray diffraction analysis found that the sample has characteristic peaks belonging to spinel, and Fourier transform infrared (FTIR) analysis found that the sample has a characteristic absorption band indicating the structure of spinel. This above findings can confirm that all samples belong to the single-phase cubic spinel structure. The average crystallite size and the lattice constant increase first and then decrease with the increase of Cr³⁺ ion content. Surface morphology analysis observed that the shape of the ferrite sample was spherical nanoparticles. The surface morphology of the sample and the stoichiometric ratio of each element contained in it are analyzed by energy-dispersive spectrometer. The sample was subjected to an external magnetic field of 15 KOe at room temperature, and a vibrating sample magnetometer was used to measure the magnetic properties of Ni_0.2Mg_0.2Co_0.6Fe_2−xCr_xO₄ nano-ferrite. Compared with other samples doped Cr³⁺ ion, the magnetic properties of the sample reach to best when the doping content is x = 0.025, and the M_s, M_r and S* (coercivity squareness) also reach the maximum at the same time.

一系列化学样品与式镍_0.2镁_0.2钴_0.6的Fe _{2- X}的Cr _X ø ₄（0.00≤  X  ≤0.1;步骤0.025）通过溶胶-凝胶自动燃烧在950℃下制备。X射线衍射分析发现样品具有属于尖晶石的特征峰，傅立叶变换红外（FTIR）分析发现样品具有指示尖晶石结构的特征吸收带。上述发现可以证实所有样品都属于单相立方尖晶石结构。随着Cr ³⁺的增加，平均晶粒尺寸和晶格常数先增大，然后减小。离子含量。表面形态分析表明，铁氧体样品的形状为球形纳米颗粒。用能量分散光谱仪分析样品的表面形态和其中所含每种元素的化学计量比。样品在室温下经受15 KOe的外部磁场，并使用振动样品磁力计测量Ni _0.2 Mg _0.2 Co _0.6 Fe _{2- x} Cr _x O ₄纳米铁氧体的磁性能。与其他掺杂Cr ³⁺离子的样品相比，当掺杂量为x  = 0.025时，样品的磁性能达到最佳。M _s，M _r和S *（矫顽力矩形度）也同时达到最大值。