Ultrafast X-Ray Diffraction Visualization of B1-B2 Phase Transition in KCl under Shock Compression
YY Zhang and YX Li and D Fan and NB Zhang and JW Huang and MX Tang and Y Cai and XL Zeng and T Sun and K Fezzaa and S Chen and SN Luo, PHYSICAL REVIEW LETTERS, 127, 045702 (2021).
The classical B1(NaCl) <-> B2(CsCl) transitions have been considered as a model for general structural phase transformations, and resolving corresponding phase transition mechanisms under high strain rate shock compression is critical to a fundamental understanding of phase transition dynamics. Here, we use subnanosecond synchrotron x-ray diffraction to visualize the lattice response of single-crystal KCl to planar shock compression. Complete B1-B2 orientation relations are revealed for KCl under shock compression along < 100 >(B1) and < 110 >(B1); the orientation relations and transition mechanisms are anisotropic and can be described with the standard and modified Watanabe-Tokonami-Morimoto model, respectively, both involving interlayer sliding and intralayer ion rearrangement. The current study also establishes a paradigm for investigating solid-solid phase transitions under dynamic extremes with ultrafast synchrotron x-ray diffraction.
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