Abstract Defect spinel Fe3-δO4 samples doped with high-valent Mo and V cations have been prepared by sol-gel auto-combustion rout with increasing concentrations of Mo and V, respectively. Energy Dispersive X-ray fluorescence (EDXRF) and Attenuated Total Reflection Fourier transform Infrared (ATR-FTIR) spectroscopies have verified the compositions of the samples and the oxidation states of the metal cations. Synchrotron Radiation X-ray Powder Diffraction (SR-XRPD) patterns were measured at MCX beamline of ELETTRA synchrotron. Structure and microstructure of the samples were studied by the Rietveld method. Increasing densities of vacancies were found to be generated by the high-valent Mo and V cations which were correlated to the lattice parameter, crystallite size and microstrain of each sample. The hysteresis loops were measured at room temperature using the Vibrating Sample Magnetometer (VSM) and good agreement was found between the Fe-cation distributions revealed from Rietveld adjustments and those predicted by the saturation magnetization (Ms) measurements. The High-Resolution Transmission Electron Microscopy (HRTEM) confirmed the proposed isotropic crystallite size model implemented in the Rietveld adjustments. Finally, the results presented herein show agreement with previous works on iron oxide materials used as intercalation cathode for Li-ion batteries and predict better performance for the current Mo- and V-doped defect spinel.

中文翻译：

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高价（Mo和V）阳离子在缺陷尖晶石氧化铁纳米材料中的作用：改善锂离子存储

摘要 通过溶胶-凝胶自燃法制备了掺杂高价 Mo 和 V 阳离子的缺陷尖晶石 Fe3-δO4 样品，分别增加 Mo 和 V 的浓度。能量色散 X 射线荧光 (EDXRF) 和衰减全反射傅里叶变换红外 (ATR-FTIR) 光谱已经验证了样品的组成和金属阳离子的氧化态。在 ELETTRA 同步加速器的 MCX 光束线处测量同步辐射 X 射线粉末衍射 (SR-XRPD) 图案。通过Rietveld方法研究样品的结构和微观结构。发现增加的空位密度是由高价 Mo 和 V 阳离子产生的，这些阳离子与每个样品的晶格参数、微晶尺寸和微应变相关。使用振动样品磁力计 (VSM) 在室温下测量磁滞回线，发现 Rietveld 调整显示的 Fe 阳离子分布与饱和磁化强度 (Ms) 测量预测的分布之间具有良好的一致性。高分辨率透射电子显微镜 (HRTEM) 证实了在 Rietveld 调整中实施的提议的各向同性微晶尺寸模型。最后，本文提出的结果与之前关于用作锂离子电池插层阴极的氧化铁材料的研究结果一致，并预测当前 Mo 和 V 掺杂的缺陷尖晶石具有更好的性能。