煅烧
材料科学
镧
化学计量学
热液循环
钙钛矿(结构)
纳米晶
化学工程
微观结构
拉曼光谱
相(物质)
扫描电子显微镜
粉末衍射
光谱学
矿物学
催化作用
无机化学
结晶学
纳米技术
物理化学
冶金
复合材料
生物化学
化学
物理
光学
有机化学
量子力学
工程类
作者
L. Tepech-Carrillo,A. Escobedo-Morales,A. Pérez-Centeno,E. Chigo Anota,José Saúl Padilla Ramírez,E. López-Apreza,Jaime Gutiérrez-Gutiérrez
摘要
A method for obtaining nanosized LaCoO 3 crystals from calcination of a precursor powder synthesized by a hydrothermal route is reported. Details concerning the evolution of the microstructure and formation mechanism of the perovskite phase were studied by powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy, and thermal analysis. It was found that the morphology of the sample progressively turns from a mix of fibers and rods to interconnected nanocrystals. It is determined that LaCoO 3 phase is produced by a reaction of cobalt and lanthanum oxides, the latter produced by a two-step dehydration process of La(OH) 3 . Finally, it was found that nearly stoichiometric LaCoO 3 nanocrystals can be obtained at temperatures as low as 850°C. Nevertheless, whether higher calcination temperatures are used, appropriate reaction times and a controlled atmosphere are required in order to avoid formation of lanthanum carbonates and high density of lattice defects.
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