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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。
In this paper, the B3LYP density functional method was used to study the microscopic reaction mechanism of BaTiO3, SrTiO3 and TiO2 dimerized to form Ti2O4 by BaO, SrO and TiO2, and the corresponding intermediates, transition states and reaction activation energies were obtained. The natural bond orbital NBO method was used to analyze the bond formation, the interaction between orbitals and the charge of each atom during the reaction. The calculated results show that the activation energies of formation of BaTiO3, SrTiO3 and Ti2O4 are 16.3, 17.3 and 9.6 kJ / mol, respectively. The activation energies of the dimer formed by TiO2 are relatively small, and the TiO2 dimer was theoretically explained. However, during the formation of BaTiO3 and SrTiO3 from SrO, BaO and TiO2, the initial stable intermediates were exothermic 484.7 and 534.7 kJ / mol, respectively, with lower activation energy, strong orbital interaction, significant electrostatic attraction, It is in favor of the nucleation and growth of SrTiO3 and Ba-TiO3 films combined with BaO and SrO at the initial stage of growth, which is in favor of the further formation of unit cell.