摘要
本文采用B3LYP密度泛函方法,研究了BaO、SrO与TiO2形成BaTiO3、SrTiO3及TiO2二聚形成Ti2O4的微观反应机理,获得了相应的中间体、过渡态及反应活化能。采用自然键轨道NBO方法分析了反应过程中各中间体和过渡态的成键情况、轨道间的相互作用以及原子的电荷。计算结果表明,形成BaTiO3、SrTiO3和Ti2O4反应活化能分别为16.3、17.3和9.6 kJ/mol,TiO2形成二聚体活化能相对较小,从理论上解释了实验过程中观测到TiO2二聚体;但SrO、BaO和TiO2形成BaTiO3、SrTiO3的反应过程中,形成最初的稳定中间体时分别放热484.7和534.7 kJ/mol,且活化能较低,轨道间相互作用较强,静电引力作用显著,有利于SrTiO3和Ba-TiO3薄膜生长初期以TiO2为中心,结合BaO和SrO成核生长,从而有利于单元胞的进一步形成。
Density functional theory（DFT） is applied to study microscopic reaction mechanism of the formation of BaTiO3 and Sr- TiO3 by BaO,SrO and TiO2 molecules and Ti204by two TiO2 molecules. The reaction intermediates, transition states and activation energies have been obtained. NBO is used to analyze bonding process, orbital interactions and atomic charges in intermediates and transition states of the reaction process. The calculated results show activation energies of the formation of BaTiO3 ,SrTiO3and Ti204 are respectively 16. 3,17. 3 and 9. 6 kJ/mol. Activation energies of Ti204 is relatively lower,TiO2 dimer observed in the experiment can theoretically be explained. However, the reaction enthalpies of the formation of the first intermediates of BaTiO3 and SrTiO3 are respectively-484. 7 and-534. 7 kJ/mol. Activation energies are low. And strong orbital interactions and static gravitations are found in molecules. These results indicate that BaO and SrO acts as a combining center TiO2in the early growth of BaTiO3and SrTiO3thin films,which should be propitious to form of primary unit cell.
出处
《化学研究与应用》
CAS
CSCD
北大核心
2012年第10期1528-1533,共6页
Chemical Research and Application
基金
国家自然科学基金(51172150)
四川省教育厅自然科学基金(11ZA110)资助项目
