The effect of the concentration of citric acid and pH values on the preparation of MgAl₂O₄ ultrafine powder by citrate sol–gel process

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• 作者：Haijun ; Zhang ; Xiaolin ; Jia ; Yongjie ; Yan ; Zhanjie ; Liu ; Daoyuan ; Yang ; Zhenzhen ; Li
• 关键词：A. Nanostructures ; A. Inorganic compounds ; A. Oxides ; B. Sol&ndash ; gel chemistry ; C. X-ray diffraction
• 刊名：Materials Research Bulletin
• 出版年：2004
• 期刊代码：60_00255408
• 类别：ms
• 出版时间：May 5, 2004
• 卷：39
• 期：6
• 页码：839-850
• 文件大小：442 K

摘要

Ultrafine MgAl₂O₄ was synthesized by citrate sol–gel process. A model was presented to evaluate the concentration of species in a citric solution for preparing MgAl₂O₄ ultrafine powder. The evaluated concentration of species can provide valuable information and help in selecting the optimal condition for preparation of MgAl₂O₄ powder by citrate sol–gel process. The influence of molar ratio of cations, citric acid and pH on the formation of MgAl₂O₄ was studied. The spinel precursor gel and the ultrafine MgAl₂O₄ spinel were characterized by X-ray diffraction (XRD), differential thermal analysis, thermogravimetric (TG-DTA) and scanning electron microscope (SEM). The results show that the MgAl₂O₄ spinel phase begins to form at 600°C, and most of MgAl₂O₄ crystals are spherical with a crystal size about 30–50nm.