YANG Kang，YANG Liang，LIN Shiwei
(College of Materials and Science Engineering, Hainan University, Haikou 570228, Hainan, China)

Abstract: Due to their excellent stability, ultra-high surface area and quantum size effect, TiO₂ nanotubes are widely used in the fields of hydrogen storage, photocatalysis, energy storage and bio-medicine. A large number of scholars have studied the electrical, optical, electrochemical and biocompatibility properties of TiO₂ nanotubes, but the studies on the mechanical properties of TiO₂ nanotubes are relatively scarce. In this paper, the mechanical properties of different chiral TiO₂ nanotubes with temperature changing are studied by molecular dynamics method. The simulation results show that when the chiral angle θ is 36.49° or 0°, the tensile strength of the TiO₂ nanotubes decreases with the temperature rising by exponential attenuation. When the chiral angle θ is 10.47°, 20.29° or 90°, the tensile strength of the TiO₂ nanotubes first reduces then increases with temperature rising. By atomic scale structure analysis, it is found that the mechanical properties of TiO₂ nanotubes are directly related to the proportions of simple cubic, BCC, FCC and HCP phase structures which occur in them with the increase of the strain in the tensile process. After stretching, the fracture of different bonds has a direct effect on tensile strength: the fracture of Ti_6c-O_3c bond reduces the tensile strength, and the fracture of Ti_5c-O_3c bond causes the tensile strength to increase first and then decrease.
Key words: molecular dynamics; TiO₂ nanotube; tensile deformation; chiral angle