高温高压下钼的结构稳定性研究

Structural stability of Mo under high pressure and high temperature

以钼为代表的一系列过渡金属,在高温高压的相变及结构稳定性研究是实验和理论研究的热点.钼在常温常压下是bcc结构,但是在高温高压下可能的相结构一直未能确定.本文首先预测了几种高压下的结构,并计算了其自由能及力学性质.针对可能的hcp结构,我们通过新近发展的自洽晶格动力学方法,充分考虑声子间相互作用,成功获得了hcp结构高温高压声子色散曲线,结果表明hcp相在热力学及动力学上都是能够稳定存在的结构,是一种可能的高压相.

The phase transition and structure stability of transition metals, such as Mo, Ta and W, have always attracted much attention of the experimental and theoretical investigators. The stable phase of Mo at room condition is bcc structure, but the high pressure and high temperature phase is questionable. We predicted the possible structures under high pressure, and obtained the free energy and the elastic properties. As hcp Mo is the possible high pressure phase, we calculated the high pressure and high temperature phonon dispersions of hcp Mo by using the newly developed SCAILD method, which can well consider thephonon - phonon interactions. By analyzing the thermodynamics and lattice dynamics, the hcp Mo can stabilize under high pressure and high temperature.