High pressure structural study of TATB: Evidence of a structural phase transition.
ORAL
Abstract
High pressure unreacted isothermal equations of state (EOS) for energetic materials are needed for accurate modeling of detonation and shock initiation. EOS determination through conventional powder X-ray diffraction (XRD) experiments is often problematic due to the low-Z of constituent elements (typically CHNO) and the low symmetry of the corresponding crystal structure. To overcome this barrier for TATB, we performed a concomitant powder and single crystal (SC) XRD study. Our SC XRD results reveal a structural phase transition, reported for the first time, towards a monoclinic C-centered structure above 4-5GPa. Experimental results are supported by calculations using the USPEX evolutionary crystal structure prediction algorithm. The phase transition involves a pressure-induced alteration of the stacking of the layers of the TATB molecules. This results to a higher crystal symmetry, from triclinic to monoclinic, without an abrupt change of the volume per formula unit.
*This work was performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Security, LLC under Contract DE-AC52-07NA27344. We thank the high explosives science campaign II research program at LLNL for supporting this study.
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Presenters
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Elissaios Stavrou
- Lawrence Livermore National Laboratory
- Lawrence Livermore Natl Lab