柠檬酸络合法制备La2CuO4纳米晶

摘要

以硝酸镧和硝酸铜为起始原料,柠檬酸为络合剂,采用溶胶-凝胶法制备了La2CuO4纳米晶.通过X射线衍射、场发射扫描电子显微镜、透射电子显微镜研究了柠檬酸的加入量对La2CuO4纳米粉体相组成、显微结构的影响,并采用Kissinger方法研究了La2CuO4纳米晶的合成活化能.结果表明:600℃煅烧保温2h后,可获得单一物相的 La2cuO4,晶粒为类钙钛矿型结构,晶粒尺寸为60～80 nm,分布集中;在制备过程中提高柠檬酸的加入量能够降低La2CuO4晶体的合成活化能,当柠檬酸与溶液中阳离子(La3+和Cu2+的物质的量的比由1∶1增加至1.5∶1时,La2CuO4纳米晶的合成活化能由147.0 kJ·mol-1降低到133.4 kJ·mol-1.%La2CuO4 nanocrystallites were prepared via a sol-gel process using lanthanum nitrate and cupric nitrate as raw materials and citric acid as complexing agent. The influences of citric acid amount on the phase composition and microstructure of the powders were characterized by XRD, FESEM and TEM. The preparation activation energy of La2CuO4 crystallites was investigated by Kissinger method. The results show that pure La2CuO4 nanocrystallites can be obtained after calcining at 600℃ for 2 h and exhibit an perovskite-like type structure, the grain size is 60-80 nm with narrow distribution. The preparation activation energy of La2CuO4 nanocrystallites can be decreased by elevating the amount of citric acid, with the increase of the molar ratio of citric acid to cations (La3+ and Cu2+) in the solution from 1:1 to 1.5:1, the preparation activation energy decreases from 147.0 kJ·mol-1 to 133.4 kJ·mol-1.