Abstract

This paper studies the application of the sol–gel method in the synthesis of M-ferrite of the composition Sr_xBa_{(1 – x)}Fe₁₂O₁₉ (х = 0, 0.3, 0.5, 0.7, 1). The synthesis procedure is based on preparing a gel from citric acid and barium, strontium, and iron nitrates, its calcination at 500°C, mechanochemical activation, and recalcination at 700°C. The target product is a dark brown powder; it was studied using X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy, and differential scanning calorimetry (DSC). The single-phase state of the synthesized samples has been confirmed by powder X-ray diffraction. Examination of the X-ray diffraction patterns of the synthesized hexaferrites and the X-ray diffraction patterns of the ICDD reference compounds reveals that all diffraction peaks coincide. The unit cell parameters of the samples calculated from X-ray diffraction patterns depend linearly on the degree of substitution of barium in hexaferrite according to the Vegard rule for solid solutions, which confirms the successful substitution of barium ions for strontium ions in the structure of barium hexaferrite. The morphological parameters of the particles of the obtained solid solutions were studied using SEM. Examining the electron microscopic images shows that particles of an average size of 50 nm formed in all the solid solutions. The average size of the coherent scattering regions, as calculated by the Scherrer equation, was 25 nm. The regular hexagon faceting characteristic of hexaferrite particles cannot be observed in SEM images because these particles are too small. Mapping of the images indicates a high level of homogenization of the initial reagent under the selected synthesis conditions. DSC yielded the values of the Curie temperature for each level of substitution with the Curie temperature increasing with the substitution level.

中文翻译：

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SrxBa(1 – x)Fe12O19 六角铁氧体钡纳米分散固溶体溶胶-凝胶合成

摘要

本文研究了溶胶-凝胶法在合成组成为 Sr _x Ba _{(1 – x )} Fe ₁₂ O ₁₉ ( х ) 的 M-铁氧体中的应用。= 0, 0.3, 0.5, 0.7, 1)。合成过程基于用柠檬酸和硝酸钡、硝酸锶和硝酸铁制备凝胶，在 500°C 下煅烧，机械化学活化，然后在 700°C 下再煅烧。目标产物为深棕色粉末；使用 X 射线衍射分析 (XRD)、扫描电子显微镜 (SEM)、能量色散 X 射线光谱和差示扫描量热法 (DSC) 对它进行了研究。粉末X射线衍射证实了合成样品的单相状态。对合成的六方铁氧体的 X 射线衍射图和 ICDD 参考化合物的 X 射线衍射图的检查表明，所有衍射峰都是一致的。根据固溶体的 Vegard 规则，根据 X 射线衍射图计算出样品的晶胞参数与六方铁氧体中钡的取代度呈线性关系，这证实了钡离子成功取代了钡结构中的锶离子六角铁氧体。使用SEM研究了所得固溶体颗粒的形态参数。检查电子显微镜图像表明，所有固溶体中均形成了平均尺寸为 50 nm 的颗粒。根据谢乐方程计算，相干散射区域的平均尺寸为 25 nm。六方铁氧体颗粒的正六边形刻面特征无法在 SEM 图像中观察到，因为这些颗粒太小。图像映射表明初始试剂在选定的合成条件下具有高水平的均质化。DSC 得出每个取代水平的居里温度值，居里温度随着取代水平的增加而增加。