Brown S Brennan, Gleason A E, Galtier E, Higginbotham A, Arnold B, Fry A, Granados E, Hashim A, Schroer C G, Schropp A, Seiboth F, Tavella F, Xing Z, Mao W, Lee H J, Nagler B
Department of Mechanical Engineering, Stanford University, Building 530, 440 Escondido Mall, Stanford, CA 94305, USA.
Shock and Detonation Physics, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545, USA.
Sci Adv. 2019 Mar 8;5(3):eaau8044. doi: 10.1126/sciadv.aau8044. eCollection 2019 Mar.
Under rapid high-temperature, high-pressure loading, lattices exhibit complex elastic-inelastic responses. The dynamics of these responses are challenging to measure experimentally because of high sample density and extremely small relevant spatial and temporal scales. Here, we use an x-ray free-electron laser providing simultaneous in situ direct imaging and x-ray diffraction to spatially resolve lattice dynamics of silicon under high-strain rate conditions. We present the first imaging of a new intermediate elastic feature modulating compression along the axis of applied stress, and we identify the structure, compression, and density behind each observed wave. The ultrafast probe x-rays enabled time-resolved characterization of the intermediate elastic feature, which is leveraged to constrain kinetic inhibition of the phase transformation between 2 and 4 ns. These results not only address long-standing questions about the response of silicon under extreme environments but also demonstrate the potential for ultrafast direct measurements to illuminate new lattice dynamics.
在快速高温、高压加载下，晶格呈现出复杂的弹性-非弹性响应。由于样品密度高以及相关的空间和时间尺度极小，这些响应的动力学在实验上难以测量。在这里，我们使用一台X射线自由电子激光，它能同时进行原位直接成像和X射线衍射，以在高应变率条件下对硅的晶格动力学进行空间分辨。我们首次成像了一种新的中间弹性特征，该特征调节沿外加应力轴的压缩，并且我们确定了每个观测波背后的结构、压缩和密度。超快探测X射线实现了对中间弹性特征的时间分辨表征，利用这一表征来限制2到4纳秒之间相变的动力学抑制。这些结果不仅解决了关于硅在极端环境下响应的长期问题，还展示了超快直接测量揭示新晶格动力学的潜力。
