Deducing density and strength of nanocrystalline Ta and diamond under extreme conditions from X-ray diffraction

YY Zhang and MX Tang and Y Cai and JC E and SN Luo, JOURNAL OF SYNCHROTRON RADIATION, 26, 413-421 (2019).

DOI: 10.1107/S1600577518017216

In situ X-ray diffraction with advanced X-ray sources offers unique opportunities for investigating materials properties under extreme conditions such as shock-wave loading. Here, Singh's theory for deducing high-pressure density and strength from two-dimensional (2D) diffraction patterns is rigorously examined with large-scale molecular dynamics simulations of isothermal compression and shock-wave compression. Two representative solids are explored: nanocrystalline Ta and diamond. Analysis of simulated 2D X-ray diffraction patterns is compared against direct molecular dynamics simulation results. Singh's method is highly accurate for density measurement (within 1%) and reasonable for strength measurement (within 10%), and can be used for such measurements on nanocrystalline and polycrystalline solids under extreme conditions (e.g. in the megabar regime).

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