Phase transition lowering in dynamically compressed silicon
Phase transition lowering in dynamically compressed silicon
复制标题
DOI：
10.1038/s41567-018-0290-x
复制
发表时间：
2019-01-01
期刊：
影响因子：
19.6
通讯作者：
Higginbotham, A.
中科院分区：
文献类型：
--
作者：
McBride, E. E.;Krygier, A.;Higginbotham, A.
硅是自然界中含量最丰富的元素之一，引起了广泛的科学和技术兴趣。具体地说，在其元素形式下，可以产生非常纯度的晶体。人们可能会认为，这将导致硅被很好地理解，事实上，这是许多环境属性的情况下，以及准静态负载下的高压行为。然而，尽管研究了几十年，硅对快速压缩的反应的详细了解-例如在冲击冲击下经历的反应-仍然是难以捉摸的。在这里，我们结合联合收割机一种新的自由电子激光为基础的X射线衍射几何与激光驱动的压缩，以阐明在冲击压缩过程中产生的剪切相变的发生的重要性。我们观察到降低的流体静力相界元素硅，一个理想的模型系统，用于调查高强度材料，类似于行星成分。此外，我们毫不含糊地确定14 GPa以上的熔融开始，以前归因于固-固相变，在现在的传统的冲击衍射几何检测不到的;预计在足够高的压力和温度下，在所有系统中普遍存在的液体状态的转变。
Silicon, being one of the most abundant elements in nature, attracts wide-ranging scientific and technological interest. Specifically, in its elemental form, crystals of remarkable purity can be produced. One may assume that this would lead to silicon being well understood, and indeed, this is the case for many ambient properties, as well as for higher-pressure behaviour under quasi-static loading. However, despite many decades of study, a detailed understanding of the response of silicon to rapid compression-such as that experienced under shock impact-remains elusive. Here, we combine a novel free-electron laser-based X-ray diffraction geometry with laser-driven compression to elucidate the importance of shear generated during shock compression on the occurrence of phase transitions. We observe lowering of the hydrostatic phase boundary in elemental silicon, an ideal model system for investigating high-strength materials, analogous to planetary constituents. Moreover, we unambiguously determine the onset of melting above 14 GPa, previously ascribed to a solid-solid phase transition, undetectable in the now conventional shocked diffraction geometry; transitions to the liquid state are expected to be ubiquitous in all systems at sufficiently high pressures and temperatures.