High Pressure and High Temperature Effects in Melt-Castable Energetics*

High-performance melt-castable energetic (MCE) materials offer an attractive alternative to benchmark energetics. Despite these prospects, processes governing the phase behavior in MCEs are poorly recognized, hindering the effective development of energetics with required macroscopic properties. Of particular interest are pressure and temperature effects, because they can change the balance between the crystalline and molten forms and, thus, affect material processability, stability, and performance. In this work, high energy density, melt-castable crystals of BNFF, BNFF-1, and TNAZ, with different melting temperatures, were subjected to combined pressure and temperature conditions. Molecular, crystalline, and morphological changes were monitored with Raman spectroscopy and optical imaging. Additional insight into underlying processes was obtained using DFT-D3 calculations. The results revealed several common properties for all materials, including: (i) structural and chemical stability over a broad range of pressure, (ii) supercooled fluid behavior upon cooling from melt, (iii) significant increase of melting temperature with pressure, and (iv) relatively low compressibility. Interplay between observed P-T responses and molecular-level features and processes are discussed.