Studies on an ionic compound (3-ATz)+ (NTO)–: crystal structure, specific heat capacity, thermal behaviors and thermal safety

Abstract

A new ionic compound (3-ATz)+ (NTO)– was synthesized by the reaction of 3-amino-1,2,4-triazole (3-ATz) with 3-nitro-1,2,4-triazol-5-one (NTO) in ethanol. The single crystals suitable for X-ray diffraction measurement were obtained by crystallization at room temperature. The crystal is monoclinic, space group p2(1)/c with crystal parameters of a = 0.6519(2) nm, b = 1.9075(7) nm, c = 0.6766(2) nm, β = 94.236(4)°, R1 = 0.0305 and wR2 = 0.0789. The thermal behaviors were studied, and the apparent activation energy and pre-exponential constant of the exothermic decomposition stage were obtained by Kissinger’s method and Ozawa’s method. The self-accelerating decomposition temperature is 505.40 K, and the critical temperature of the thermal explosion is obtained as 524.90 K. The specific heat capacity was determined with Micro-DSC method and the theoretical calculation method, and the standard molar specific heat capacity is 221.31 J mol−1 K−1 at 298.15 K. The Gibbs free energy of activation, enthalpy of activation, and entropy of activation are 151.55 kJ mol−1, 214.52 kJ mol−1 and 122.44 J mol−1 K−1. The adiabatic time-to-explosion of the compound was estimated to be a certain value between 5.0 and 5.2 s, and the detonation velocity (D) and pressure (P) were also estimated using the nitrogen equivalent equation according to the experimental density.