High pressure-high temperature phase diagram of an energetic crystal: Dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50)

Raman spectroscopy was used to examine the high pressure-high temperature structural and chemical stability of an insensitive, high-performance energetic crystal - dihydroxylammonium 5,5'-bistetra zole-1,1'-diolate (TKX-50). The phase diagram was determined over 8 GPa and (293-760) K. Under isobaric heating, the melting/decomposition of TKX-50 is preceded by a transformation to two consecutive high-temperature intermediates; a lower-temperature intermediate - diammonium 5,5'-bistetrazole-1, 1'-diolate, and a higher-temperature intermediate - dihydroxylammonium 5,5'-bistetrazolate and/or diammonium 5,5'-bistetrazolate. Pressure strongly increases the transition temperatures for these transformations and subsequent decomposition. Significant increase in the chemical stability of TKX-50 and intermediates with pressure was attributed to a suppression of hydrogen-transfer. (C) 2017 Published by Elsevier B.V.