金红石型TiO2结构随温度变化的分子动力学模拟

常压下,采用经典离子晶体相互作用势模型,并进行量子化修正,对金红石型TiO2结构随温度变化进行分子动力学模拟,计算了键长、键角、均方位移、特征(110)面分布函数及TiO6八面体结构随温度变化特性.模拟结果表明,当温度由300 K升至1 800 K时,TiO2中阴、阳离子振动偏离原来的平衡位置,均方位移逐渐增加,形成晶体的热膨胀;尤其在温度高于1 000 K时,TiO2体系中Ti-O键、键角、均方位移等特征参数出现较明显的变化,特征晶面(110)及八面体构型出现扭曲,精细结构在一定程度上受到破坏,晶体的无序度逐渐增大,呈现出短程有序、长程无序的高温非晶结构特征,这些模拟结果与相关实验结果基本一致.

Molecular dynamics simulations for microstructure of rutile TiO2 with temperature

Molecular dynamics(MD) simulations with quantum correction were used to research the microstructure of rutile TiO2 with temperature under 1atm.The distribution of bond length,bond angle,mean-square displacements(MSDs) and(110) planar distribution functions(PDFs),as well as the local octahedral structures were described using MD process.As temperature increasing,the vibration for all cations and anions displaces the equilibrium position in rutile TiO2,the MSDs enhance gradually,and the crystal expends.Up to 1 000 K,especially,the bond lengths,bond angles and MSDs change abruptly,and(110) PDFs and octahedral structures are distorted.The specific structure is destroyed,and further,disordered structure and amorphous state occur within order in short term and disorder in long term under high temperature.These results basically correspond with ones by experiment.