“Y”型、竹节型与直纳米碳管的力学特性研究

采用基于BrennerREAO(reactiveempiricalbondorder)势的分子动力学方法,模拟了“Y”型、竹节型与直纳米碳管的拉伸过程。结合有限元分析,对比并讨论了“Y”型、竹节型纳米碳管与直纳米碳管拉伸力学性能的差异。研究结果表明,拉伸“Y”型、竹节型纳米碳管的屈服与断裂均发生在其粗管与细管过渡的“应力集中”部位;“应力集中”致使“Y”型、竹节型纳米碳管的抗拉强度与韧性明显低于直纳米碳管;然而,“Y”型、竹节型碳管的弹性模量依然与直纳米碳管相当。

Y-branched TiO_2 nanotube arrays synthesized by anodic oxidation

We report a novel synthesis strategy for Y-branched TiOe nanotubes on a pure titanium foil by electrochemical anodic oxida- tion in an NH4F organic electrolyte. Effects of temperature range, oxidation time, and morphology-dependent parameters of the Y-branched TiO2 nanotube arrays were investigated. We found that an optimized growth-temperature window between 20℃ and 30℃ resulted in Y-branched nanotubes with much better morphology and photoelectric performances. After annealing at 450℃ for 1.5 h in air, a dominant crystal structure of these arrays was indexed to anatase.