The nano-crystalline mixed ferrites with the generic formula Mn_xMg_1 − xFe₂O₄ (x = 0.0–1.0, step: 0.2) were prepared by the citrate-gel auto-combustion technique. Motivated by anomalous magnetic behaviour of coarse-grained MnFe₂O₄, the main aim was to study the influence of Mn²⁺ substitution in MgFe₂O₄ on magnetic structure at nano-regime. The compositional stoichiometry of the final ferrite products was ascertained by EDAX mapping and particle size for each sample was determined by powder X-ray diffraction, TEM, small-angle X-ray and neutron scattering techniques. The lattice constant increases with Mn-content due to larger cation (Mn²⁺) substitution. The distribution of cations in the tetrahedral (A) and octahedral (B) interstitial sites of the spinel lattice is determined by X-ray diffraction and Mossbauer spectral intensity analysis. The Mossbauer spectra at room temperature exhibit two sextets due to A- and B-sites for compositions x = 0.0, 0.2 and 1.0 while spectra showed central paramagnetic doublet superimposed on magnetic sextets for the samples with x = 0.4, 0.6 and 0.8, ascribed to the presence of superparamagnetic clusters. Thermal variation of AC susceptibility showed hump near the Curie temperature due to the presence of superparamagnetic clusters as corroborated by Mossbauer signature. The observed saturation magnetic moment (at temperature 5 K and applied field 9 T) is found lower compared to Neel's moment for the compositions with x > 0.2 which is explained on the basis of the exchange disorder of Fe³⁺ ions in the B-sites in Mn-containing ferrites.

通式为Mn _x Mg _{1 -  x} Fe ₂ O ₄ ( x  = 0.0–1.0, step: 0.2)的纳米晶混合铁氧体是通过柠檬酸盐凝胶自燃技术制备的。受粗粒MnFe ₂ O ₄异常磁行为的驱动，主要目的是研究Mn ²⁺取代MgFe ₂ O _{4 的影响}纳米区域的磁性结构。最终铁氧体产品的组成化学计量通过 EDAX 映射确定，每个样品的粒度通过粉末 X 射线衍射、TEM、小角 X 射线和中子散射技术确定。由于较大的阳离子 (Mn ²⁺ ) 取代，晶格常数随着 Mn 含量的增加而增加。阳离子在尖晶石晶格的四面体 (A) 和八面体 (B) 间隙位置中的分布是通过 X 射线衍射和穆斯堡尔光谱强度分析确定的。由于成分x  = 0.0、0.2 和 1.0 的A 位点和 B 位点，室温下的穆斯堡尔光谱显示出两个六重峰，而光谱显示中央顺磁双峰叠加在具有x的样品的磁性六重峰上 = 0.4、0.6 和 0.8，归因于超顺磁性簇的存在。由于 Mossbauer 特征所证实的超顺磁性簇的存在，交流磁化率的热变化显示出接近居里温度的驼峰。观察到的饱和磁矩（在温度 5 K 和外加场 9 T 下）与x  > 0.2的组合物的 Neel 磁矩相比较低，这是根据B 位中 Fe ³⁺离子的交换无序解释的在含锰铁氧体中。