observation of a phase transition in silicon carbide under shock compression using pulsed x-ray diffraction
- Princeton Univ., Princeton, NJ (United States)
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Institute for Materials and Energy Science (SIMES)
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Univ. of Chicago, IL (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
- GFZ German Research Centre for Geosciences, Potsdam (Germany)
- European X-ray Free-Electron Laser (XFEL), Hamburg (Germany)
- SLAC National Accelerator Lab., Menlo Park, CA (United States). Linac Coherent Light Source (LCLS)
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.
- Research Organization:
- SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- SC0016242; AC52-07NA27344; AC02-76SF00515
- OSTI ID:
- 1546744
- Alternate ID(s):
- OSTI ID: 1546309
- Journal Information:
- Physical Review B, Journal Name: Physical Review B Journal Issue: 21 Vol. 99; ISSN 2469-9950; ISSN PRBMDO
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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