摘要
采用水热法,利用乙醇和水的混合溶剂合成了单分散钛酸锶纳米晶体。X射线衍射(XRD)结果显示该晶体为立方相,延长反应时间其结晶性增强。扫描电子显微镜(SEM)、透射电子显微镜(TEM)结果显示样品为70 nm左右的均匀立方块晶体。利用SEM、TEM、高分辨透射电子显微镜(HRTEM)和电子衍射(ED)谱研究了该纳米晶体的生长过程,结果表明:前驱体经过扩散反应生成钛酸锶晶核,晶核之间由于定向生长作用而团聚连接形成颗粒球,最后颗粒球在缓慢的奥斯特瓦尔德熟化作用下转化为钛酸锶晶体。这一"扩散反应、定向生长、奥斯特瓦尔德熟化"的生长过程揭示了钛酸锶纳米晶体的生长机理。利用Johnson-MehlAvrami(JMA)方程模拟证实了其初始阶段的扩散反应机理,并得出反应活化能为15.79 k J·mol-1。
In the mixed-solution of ethanol and water, the monodisperse strontium titanate（STO） nanocrys-tallines were synthesized by hydrothermal method. The powder X-ray diffraction（XRD） patterns results revealed that the nanocrystallines crystallized in the cubic phase, and the crystallization of the products became more significant with the reaction continuing. The particle size of about 70 nm and cubic morphology were further evidenced by the scanning electron microscopy（SEM） and transmission electron microscopy（TEM）. The growth process of the nanocrystallines was studied by SEM, TEM, high resolution transmission electron microscopy（HRTEM） and electron diffraction（ED） spectroscopy in detail. The results have discovered that as follow： first, the nucleus of STO was produced by the diffusion reaction between the precursors; then, the nuclei orientedly attached by each other and the nanoparticle-aggregation came into being; last, the nanoparticle-aggregations were converted into the single crystallines of STO under Ostwald ripening mechanisms. The growth process of ＂diffusion reaction—oriented attachment—Ostwald ripening＂ has discovered the formation mechanism of STO nanocrystalline. The results of kinetics modeling with Johnson-Mehl-Avrami（JMA） equation show that the diffusion reaction is dominant at the early stage and the active energy is 15.79 k J·mol^-1.
出处
《无机化学学报》
SCIE
CAS
CSCD
北大核心
2015年第5期888-894,共7页
Chinese Journal of Inorganic Chemistry
基金
国家自然科学基金(No.51262009)
江西省自然科学基金(No.20122BAB203019,20132BAB206017,20122BAB202001)
江西省教育厅科技项目(No.GJJ13628)
江西省高校大学生创新创业计划项目(No.201310408019)
江西省高校中青年教师发展计划访问学者项目资助
关键词
钛酸锶
JMA方程
定向生长
strontium titanate
JMA equation
oriented attachment
