摘要
采用湿化学法在常压及温度低于 10 0℃的水溶液中 ,使锂盐与锰盐发生化学反应生成LiMn2 O4 化合物 ,经过滤、洗涤后 ,在 10 5℃时烘干制得无定型LiMn2 O4 化合物的前驱体 .借助于X射线衍射及扫描电镜等现代测试手段研究了热处理温度及热处理时间对湿化学法合成LiMn2 O4 晶型结构及形貌的影响 .结果表明 ,所得前驱体经适当的高温热处理可获得晶型结构完整的尖晶石型LiMn2 O4 ;热处理温度对LiMn2 O4 的晶体结构影响较大 ,随着热处理温度的升高 ,其X射线衍射峰的强度明显增大 ,晶体的结构趋于完整 ,且晶粒明显变粗 ;当热处理温度为 5 0 0℃时 ,除LiMn2 O4 的衍射峰外 ,未见其它杂相的衍射峰 ,说明无定型的LiMn2 O4 已完全转变为尖晶石结构 ;在 70 0℃时热处理4h即可获得晶型结构完整、晶界分明、粒度均匀的LiMn2 O4 ;而热处理时间对LiMn2 O4 的晶型结构影响不大 ,相同温度下随热处理时间的延长 。
A LiMn 2O 4 compound was synthesized in aqueous solution from lithium compound which reacted with manganese compound by means of wet chemical technique at normal atmosphere and temperature of less than 100 ℃. After being filtered and washed with water, then dried at 105 ℃, the precursor of LiMn 2O 4 compound with an amorphous structure can be obtained. The changes in the crystal structure and the shape of LiMn 2O 4 samples with the calcinating temperature and time were detected by means of X ray diffraction and scanning electron micrograph. The results show that perfect spinel LiMn 2O 4 crystals can be obtained from the precursor of LiMn 2O 4 after being calcinated. It is concluded that the calcinating temperature has great influences on the crystal structure of LiMn 2O 4. With the elevating of the temperature, the crystal structure becomes more perfect and the particle size gets larger. Only LiMn 2O 4 XRD patters can be observed when the sample is calcined at 500 ℃ and it is showed that the structure of LiMn 2O 4 compound is completely transformed from amorphous to spinel. A spinel type LiMn 2O 4 with regular crystal structure and well distributed particle size can be obtained after being calcinated for 4 h at 700 ℃. However, it is also observed that the calcinating time has less effect on the perfection of the LiMn 2O 4 structure and the samples almost maintain the same XRD patterns when the calcinating time is prolonged at the same temperature.
出处
《中南工业大学学报》
CSCD
北大核心
2001年第2期131-134,共4页
Journal of Central South University of Technology(Natural Science)
基金
国家教育部高等学校骨干教师计划资助项目 !(教技师 [2 0 0 0 ] 65号 )
