Santamaría-Pérez D, Ross M, Errandonea D, Mukherjee G D, Mezouar M, Boehler R
Max-Planck Institute für Chemie, Postfach 3060, D-55020 Mainz, Germany.
J Chem Phys. 2009 Mar 28;130(12):124509. doi: 10.1063/1.3082030.
In this paper, we report angle-dispersive X-ray diffraction data of molybdenum melting, measured in a double-sided laser-heated diamond-anvil cell up to a pressure of 119 GPa and temperatures up to 3400 K. The new melting temperatures are in excellent agreement with earlier measurements up to 90 GPa that relied on optical observations of melting and in strong contrast to most theoretical estimates. The X-ray measurements show that the solid melts from the bcc structure throughout the reported pressure range and provide no evidence for a high temperature transition from bcc to a close-packed structure, or to any other crystalline structure. This observation contradicts earlier interpretations of shock data arguing for such a transition. Instead, the values for the Poisson ratios of shock compressed Mo, obtained from the sound speed measurements, and the present X-ray evidence of loss of long-range order suggest that the 210 GPa (approximately 4100 K) transition in the shock experiment is from the bcc structure to a new, highly viscous, structured melt.
在本文中，我们报告了钼熔化的角散射X射线衍射数据，这些数据是在双面激光加热金刚石对顶砧池中测量的，压力高达119吉帕，温度高达3400开尔文。新的熔化温度与早期高达90吉帕的测量结果非常吻合，早期测量依赖于熔化的光学观测，并且与大多数理论估计形成强烈对比。X射线测量表明，在所报道的压力范围内，固体从体心立方结构熔化，没有提供证据表明存在从体心立方结构到密排结构或任何其他晶体结构的高温转变。这一观察结果与早期对冲击数据的解释相矛盾，早期解释认为存在这样的转变。相反，从声速测量中获得的冲击压缩钼的泊松比的值，以及目前X射线关于长程有序丧失的证据表明，冲击实验中210吉帕（约4100开尔文）的转变是从体心立方结构到一种新的、高粘性的、结构化熔体。
