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用乙二胺四乙酸(EDTA)作为辅助络合剂与Ca2+单独络合,然后再与柠檬酸络合剂混合,解决了柠檬酸络合剂与Ca2+络合能力差的问题,实现了La3+、Cr3+、Ca2+三种离子在溶胶中的均匀稳定络合。利用红外光谱、热分析、X射线衍射、透射电镜对凝胶结构、热分解过程、粉体物相等进行了表征。结果表明,该工艺得到的干凝胶在500℃煅烧就可以转变为纯度较高的La0.9Ca0.1CrO3相,比单一柠檬酸体系的合成温度低200℃左右。另外,该体系中钙掺杂起到抑制铬酸镧中Cr元素挥发的作用。
Using ethylenediaminetetraacetic acid (EDTA) as an auxiliary complexing agent to complex with Ca2 + alone and then mixing with citric acid complexing agent to solve the problem that the complexing ability between citric acid complexing agent and Ca2 + is poor, and realizing the problems of La3 + Cr3 +, Ca2 + three ions in the sol uniform stable complex. The structure of the gel, thermal decomposition process and powder phase were characterized by infrared spectroscopy, thermal analysis, X-ray diffraction and transmission electron microscopy. The results show that the calcined xerogel at 500 ℃ can be transformed into La0.9Ca0.1CrO3 phase with a purity of about 200 ℃ lower than that of single citric acid system. In addition, the calcium doping in the system plays a role of inhibiting Cr elemental volatilization in lanthanum chromite.