摘要:
基于密度泛函理论研究了纤铁矿和锐钛矿型TiO2纳米管的原子结构、稳定性、Young模量以及电子能带结构.计算结果显示:在纳米管直径较小时,锐钛矿型TiO_2纳米管的稳定性要好于纤铁矿型纳米管,随着管径的增大,纤铁矿型纳米管变得比锐钛矿型纳米管要更稳定.纤铁矿型TiO_2纳米管具有比锐钛矿型纳米管更大的Young模量,力学性能比较优异.另外,通过对电子能带结构的研究发现,手性对TiO_2纳米管的电子结构影响较大,纤铁矿(0,n)型和锐钛矿(n,0)型纳米管为间接带隙半导体,而纤铁矿(n,0)型和锐钛矿(0,n)型纳米管却具有直接带隙.
Abstract:
The structure, stability, Young's modulus and electronic band structures of lepidocrocite-type and anatase-type TiO_2 nanotubes were investigated using density functional theory calculation. It was found that the anatase-type nanotubes were energetically more favorable than lepidocrocite-type nanotubes when the diameter of nanotube is small, whereas the lepidocrocite type nanotubes were energetically more favorable when the diameter of nanotube was large. Young's modulus of TiO_2 nanotubes is calculated. The results obtained show that all TiO_2 nanotubes have relatively good mechanical properties, and lepidocrocite nanotubes are stronger than anatase nanotubes. Interestingly, it was found that the electronic band structures of TiO_2 nanotubes are influenced by the tubular chirality. Lepidocrocite (0, n) and anatase ( n, 0) nanotubes are of indirect band gap type, whereas lepidocroctie (n, 0) and anatase (0, n) nanotubes have direct band gaps.
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