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In situ observation of a phase transition in silicon carbide under shock compression using pulsed x-ray diffraction

Author(s): Tracy, Sally J; Smith, Raymond F; Wicks, June K; Fratanduono, Dayne E; Gleason, Arianna E; et al

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Abstract: The behavior of silicon carbide (SiC) under shock compression is of interest due to its applications as a high-strength ceramic and for general understanding of shock-induced polymorphism. Here we use the Matter in Extreme Conditions beamline of the Linac Coherent Light Source to carry out a series of time-resolved pump-probe x-ray diffraction measurements on SiC laser-shocked to as high as 206 GPa. Experiments on single crystals and polycrystals of different polytypes show a transformation from a low-pressure tetrahedral phase to the high-pressure rocksalt-type (B1) structure. We directly observe coexistence of the low- and high-pressure phases in a mixed-phase region and complete transformation to the B1 phase above 200 GPa. The densities measured by x-ray diffraction are in agreement with both continuum gas-gun studies and a theoretical B1 Hugoniot derived from static-compression data. Time-resolved measurements during shock loading and release reveal a large hysteresis upon unloading, with the B1 phase retained to as low as 5 GPa. The sample eventually reverts to a mixture of polytypes of the low-pressure phase at late times. Our study demonstrates that x-ray diffraction is an effective means to characterize the time-dependent structural response of materials undergoing shock-induced phase transformations at megabar pressures.
Publication Date: 17-Jun-2019
Citation: Tracy, S. J., R. F. Smith, J. K. Wicks, D. E. Fratanduono, A. E. Gleason, C. A. Bolme, V. B. Prakapenka et al. "I n s i t u observation of a phase transition in silicon carbide under shock compression using pulsed x-ray diffraction." Physical Review B 99, no. 21 (2019): 214106. doi: 10.1103/PhysRevB.99.214106.
DOI: doi:10.1103/PhysRevB.99.214106
ISSN: 2469-9950
EISSN: 2469-9969
Pages: 214106
Type of Material: Journal Article
Journal/Proceeding Title: Physical Review B
Version: Final published version. Article is made available in OAR by the publisher's permission or policy.

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