Sharma Surinder M, Turneaure Stefan J, Winey J M, Gupta Y M
Institute for Shock Physics, Washington State University, Pullman, Washington 99164, USA.
Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164, USA.
Phys Rev Lett. 2020 Jun 12;124(23):235701. doi: 10.1103/PhysRevLett.124.235701.
High pressure structural transformations are typically characterized by the thermodynamic state (pressure-volume-temperature) of the material. We present in situ x-ray diffraction measurements on laser-shock compressed silver and platinum to determine the role of deformation-induced lattice defects on high pressure phase transformations in noble metals. Results for shocked Ag show a copious increase in stacking faults (SFs) before transformation to the body-centered-cubic (bcc) structure at 144-158 GPa. In contrast, shock compressed Pt remains largely free of SFs and retains the fcc structure to over 380 GPa. These findings, along with recent results for shock compressed gold, show that SF formation promotes high pressure structural transformations in shocked noble metals that are not observed under static compression. Potential SF-related mechanisms for fcc-bcc transformations are discussed.
高压结构转变通常由材料的热力学状态（压力-体积-温度）来表征。我们对激光冲击压缩的银和铂进行了原位X射线衍射测量，以确定变形诱导的晶格缺陷在贵金属高压相变中的作用。冲击后的银的结果表明，在144-158吉帕转变为体心立方（bcc）结构之前，堆垛层错（SFs）大量增加。相比之下，冲击压缩的铂在很大程度上没有堆垛层错，并且在超过380吉帕时仍保持面心立方（fcc）结构。这些发现，连同最近冲击压缩金的结果表明，堆垛层错的形成促进了冲击后的贵金属中的高压结构转变，而在静态压缩下未观察到这种转变。讨论了与堆垛层错相关的面心立方-体心立方转变的潜在机制。
