有机凝胶法制备掺杂铬酸镧的纳米粉体

PREPARATION OF DOPED LANTHANUM CHROMITES NANO-POWDERS BY AQUEOUS ORGANIC-GEL METHOD

以柠檬酸作络合剂,硝酸盐作起始物,采用有机凝胶法制备掺杂铬酸镧的纳米粉体。用红外光谱分析、热重分析研究纳米粉体的凝胶结构和分解过程。用X射线衍射仪和透射电镜等分析测试手段对凝胶燃烧后的纳米粉体进行表征。实验表明:在前驱体溶液中加入适量乙二醇后,用有机凝胶法得到粒径为50 nm左右的LaCrO3粉体。乙二醇在胶凝过程中起到重要的促进作用,使干凝胶分步分解。另外,实验证实了干凝胶煅烧向LaCrO3转变过程中存在过渡相。

Nano-powders of doped lanthanum chromites were prepared by the aqueous organic-gel method using citric acid as a complex agent and metal nitrate as starting materials. The structure and thermal decomposition of metal carboxylate precursor gel were investigated by infrared spectroscopy and thermogravimetry. With X-ray diffraction and transmission electron microscope, the crystal structure and morphology of the particles were characterized. Results show that LaCrO3 powder with particle size near 50 nm can be obtained by the aqueous organic-gel method when the ethylene glycol is added into the precursor solution. The ethylene glycol plays an important role in gelling process and it makes the organic-gel decomposed in several steps. The results also indicate that there is a transition phase during the transforming process of gel to LaCrO3 powder after calcination.