铬酸镧超细粉的低温燃烧合成方法研究

Low-temperature Combustion Synthesis of Lanthanum Chromites Super-fine Powder

用金属硝酸盐为阳离子源和氧化剂,硝酸铵为助燃剂低温燃烧合成了铬酸镧超细粉。用红外光谱(IR)、X射线衍射和透射电子显微镜对中间产物凝胶和燃烧后的粉末进行了分析。结果表明,当体系中加入理论比例的硝酸铵时,干凝胶没有完全燃烧,燃烧后的粉体中存在残余有机物;为了合成不含残余有机物的铬酸镧,应使凝胶中的硝酸铵适当过量,确保燃烧过程中有足够的能量使有机物完全分解。

Low-temperature combustion synthesis of lanthanum chromites （La1-.xCaxCrO3 ） super-fine powder was carried out by using lanthanum and chromium nitrate as cationic sources and oxidant, and ammonium nitrate as combustion aid. By means of the infrared spectrum （IR）, XRD and TEM, the intermediate product gel and synthesized powders were analyzed. The results show that the gel is not combusted completely and the organic remains in the combusted powders with a stoichiometric molar ratio between nitrate and combustion aid. In order to synthesize powders of lanthanum chromites without the organic remains, a suitable over-rich of the combustion aid should be adopted to make sure that there is enough energy during combustion to decompose the organic completely.