CoAl₂O₄ spinel was successfully synthesized by combustion synthesis method using glycine and urea by 1:1 molar ratio as fuels and sol‐gel process using citric acid as a chelating agent. The as‐synthesized powders were calcined at desired temperatures to obtain CoAl₂O₄ spinel as a single phase. X‐ray diffraction, thermogravimetric, and differential thermal analysis results revealed that the formation of CoAl₂O₄ spinel in combustion method needs 300°C higher temperatures than those of sol‐gel. Scanning electron microscopy and transmission electron microscopy analysis results revealed that “sol‐gel spinel” had nanometric particle size which was smaller than those of “combustion spinel.” Temperature programed reduction with hydrogen and Fourier transform infrared spectroscopy results declared that there was a little residual cobalt oxide in combustion spinel while there is no oxide resided in “sol‐gel spinel.” Consequently, the sol‐gel method has more benefit in synthesizing spinel with sulfate precursors than combustion.

中文翻译：

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柠檬酸溶胶凝胶和CoAl2O4尖晶石燃烧合成方法的比较研究

通过燃烧合成法，以甘氨酸和尿素以1：1的摩尔比为燃料，并以柠檬酸为螯合剂进行溶胶-凝胶法成功地合成了CoAl ₂ O ₄尖晶石。将合成后的粉末在所需温度下煅烧，以获得单相CoAl ₂ O ₄尖晶石。X射线衍射，热重分析和差热分析结果表明，CoAl ₂ O ₄的形成燃烧方法中的尖晶石需要比溶胶凝胶高300°C的温度。扫描电子显微镜和透射电子显微镜的分析结果表明，“溶胶-凝胶尖晶石”的纳米粒径小于“燃烧尖晶石”的粒径。用氢进行程序升温还原和傅立叶变换红外光谱分析的结果表明，在燃烧的尖晶石中几乎没有残留氧化钴，而“溶胶-凝胶尖晶石”中没有残留氧化物。因此，与燃烧相比，溶胶-凝胶法在用硫酸盐前体合成尖晶石方面具有更大的优势。