The relative orientations between the lattices of the low pressure and high pressure phases of shock compressed KCl single crystals were examined using plate impact loading along the  and the  directions. The -phase lattice planes, perpendicular to the loading direction, were determined from transient x-ray diffraction measurements. Two closely spaced diffraction peaks were observed for the  loading direction. The lower Bragg angle peak is consistent with a 200 peak of a cubic -phase unit cell giving the orientation relation is parallel to . The higher Bragg angle peak is not consistent with any peak from either a cubic or a cubic unit cell; the origin of this peak is unknown. Other experiments found no orientation relations; for the  loading direction, is not parallel to and for the  loading direction, is not parallel to . The orientation relation determined for the  loading in this work is incompatible with a previously determined orientation relation obtained for the  loading [T. d’Almeida and Y. M. Gupta, Phys. Rev. Lett. 85, 330 (2000)]. This finding suggests that the transformation pathway between the and lattices in KCl crystals depends on the shock compression direction for the phase. The results are discussed in terms of the compatibility between the macroscopic uniaxial strain imposed by shock wave loading and the microscopic rearrangement of atoms leading to the observed orientation relations.
Shock induced phase change in KCl single crystals: Orientation relations between the and lattices
Stefan J. Turneaure, Y. M. Gupta, Paulo Rigg; Shock induced phase change in KCl single crystals: Orientation relations between the and lattices. J. Appl. Phys. 1 January 2009; 105 (1): 013544. https://doi.org/10.1063/1.3065522
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