Phase transition and thermal expansion of molecular perovskite energetic crystal (C6N2H14)(NH4)(ClO4)3 (DAP-4)

Autor: Yu Shang, Lin-ying Sun, Zi-ming Ye, Shao-li Chen, Wei-xiong Zhang, Xiao-ming Chen
Jazyk: angličtina
Rok vydání: 2022
Předmět:
Zdroj: FirePhysChem, Vol 2, Iss 3, Pp 221-225 (2022)
Druh dokumentu: article
ISSN: 2667-1344
DOI: 10.1016/j.fpc.2022.01.002
Popis: Research on the structural responses to thermal stimuli for crystalline energetic materials is crucial to their practical applications. DAP-4 is a metal-free molecular perovskite high-energetic material attracting increasing attentions on its application potential as heat-resistant explosive. In order to reveal its structural responses to thermal stimuli, herein we investigated the structural phase transitions and thermal expansion of DAP-4 by DSC, single-crystal X-ray diffraction, and variable-temperature capillary powder X-ray diffraction. The results show that DAP-4 undergoes two-step reversible phase transitions at 300.4/298.9 K and 548.4/547.7 K, respectively, which are caused by two-step order-disorder transition of the molecular components during a heating/cooling cycle. The axial and the volumetric expansion coefficients of DAP-4 are estimated based on the temperature-dependent cell parameters obtained by Pawley refinement in a large temperature range of 173–353 K, and they are close to those estimated for β-HMX. Notably, although a volume change of 0.77% occur in the near-room-temperature phase transition, all the crystalline phases of DAP-4 possess cubic structures with isotropic expansibility, rather than the commonly-observed anisotropic one in the most of known energetic crystals, which may be propitious to reduce the adverse effect of its volume change on the formulation design.
Databáze: Directory of Open Access Journals