title: High pressure-high temperature polymorphism and decomposition of pentaerythritol tetranitrate (PETN).
abstract: To elucidate the behavior of PETN at thermo-mechanical conditions relevant for shock initiation, Raman spectroscopy, and optical imaging were used to examine its static high pressure and high temperature (HP-HT) response. Experiments were performed on single crystals in a heated diamond anvil cell at pressures to 14 GPa and temperatures ranging from room temperatures to 550 K. Regarding the pressure-induced PETN-I transition to PETN-III at room temperature, our results show that nonhydrostaticity plays an important role in driving this transition. Furthermore, we found that PETN-III transforms to PETN-IV at high temperatures, and this transformation can involve lowering of molecular symmetry from C2 to C1. The HP-HT phase diagram for PETN presented here includes the melting/decomposition curve and boundaries between three PETN phases: PETN-I, PETN-III, and PETN-IV. The relevance of static compression results for shock initiation of PETN is discussed.
authors.affiliation: Institute for Shock Physics and Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164-2816, USA. dreger@wsu.edu
authors.forename: Zbigniew A
authors.initials: ZA
authors.lastname: Dreger
authors.forename: Yogendra M
authors.initials: YM
authors.lastname: Gupta