"点石成金?"--碳结构超高压物理力学

文章介绍了石墨和碳纳米管在超高压和／或纳米压痕下的层间sp^2-sp^3键转化、软硬相转换、纳米硬度等研究进展．通过量子力学和分子动力学建模分析研究，发现超高压下石墨和碳纳米管存在软相向硬相转变的双相机制，给出了超高压获取石墨和碳纳米管超硬相的条件．理论计算与实验结果吻合很好，并能合理地解释有关石墨和碳纳米管超高压实验中看似矛盾的各种实验现象．提出了碳结构超高压物理力学概念，可为超高压碳相关物质相变、物化性质调控提供理论方法．

"Touch graphite and turn it into diamond?"-Physical mechanics of carbon matters under ultrahigh pressure

The research progress on interlayer sp~2 to sp~3-bonding switching of graphite and carbon nanotubes (CNTs) under ultra-highly-pressure or nano-indentation is introduced. It is found that soft to hard phase transition of both graphite and single-and multi-walled CNTs will occur at pressure of about 17GPa, at which all the interlayer distances of graphite and CNTs are approaching a critical value of 2 angstrom. Further increase of pressure will lead to interlayer sp~2 to sp~3-bond transition and sharp increase in hardness up to a stable value comparable to that of diamond. The new formed sp3 structure has strength above 100GPa which can crack a diamond anvil cell, thus explain the paradox raised in recent high-pressure experiments on graphite. We found that quantum mechanics and the molecular dynamics simulations can provide pretty coincident predictions. This shows that physical mechanics analysis can be useful tool in study of carbon matters under ultrahigh pressure.