Structural evolution of CL-20/DNB cocrystals at high temperature: Phase transition and kinetics of thermal decomposition

Xiaoyu Sun; Wentao Liang; Xiangdong Li; Di Mai; Yang Zhang; Zhilei Sui; Rucheng Dai; Xianxu Zheng; Zhongping Wang; Xiaohui Duan; Zengming Zhang

doi:10.1016/j.saa.2023.122436

Structural evolution of CL-20/DNB cocrystals at high temperature: Phase transition and kinetics of thermal decomposition

Spectrochim Acta A Mol Biomol Spectrosc. 2023 May 5:292:122436. doi: 10.1016/j.saa.2023.122436. Epub 2023 Feb 3.

Authors

Xiaoyu Sun¹, Wentao Liang², Xiangdong Li³, Di Mai³, Yang Zhang³, Zhilei Sui⁴, Rucheng Dai⁵, Xianxu Zheng⁴, Zhongping Wang⁶, Xiaohui Duan⁷, Zengming Zhang⁸

Affiliations

¹ The Center for Physical Experiments, School of Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China. Electronic address: xysun2015@ustc.edu.cn.
² Department of Physics, School of Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China. Electronic address: liangwt@mail.ustc.edu.cn.
³ Department of Physics, School of Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China.
⁴ Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, Sichuan 621900, China.
⁵ The Center for Physical Experiments, School of Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China.
⁶ The Center for Physical Experiments, School of Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China. Electronic address: zpwang@ustc.edu.cn.
⁷ Key Laboratory of Environment-friendly Energy Materials, Southwest University of Science and Technology, Mianyang 621010, China. Electronic address: duanxiaohui@swust.edu.cn.
⁸ The Center for Physical Experiments, School of Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China. Electronic address: zzm@ustc.edu.cn.

PMID: 36753867
DOI: 10.1016/j.saa.2023.122436

Abstract

As a typical new energetic material, CL-20/DNB cocrystals have been recognized as a promising explosive owing to their excellent comprehensive performance. The thermal decomposition behavior, structural evolution and dynamic process of CL-20/DNB cocrystals under high temperature were studied by means of thermogravimetric differential heating, X-ray diffraction, Raman spectroscopy to gain insight into the cocrystal materials. The study found that the decomposition of CL-20/DNB cocrystal is a heterogeneous process accompanied by the sublimation of DNB and structural change of CL-20. The phase transition of β → γ-CL-20 was observed at 120 °C. The kinetics of decomposition and the mechanism of micro structural evolution on CL-20/DNB cocrystals with heating were revealed. The primary NO⋯H hydrogen bonds of the cocrystal are broken, accompanied by the melting of DNB in the temperature range of 100-120 °C. Subsequently, the DNB single component decomposes completely, leading to lattice collapse of cocrystal; simultaneously, CL-20 undergoes a transition process from β phase to γ phase. Ultimately, γ-CL-20 gradually decomposes with increasing temperature. The activation energy of cocrystal is also obtained as 129 ± 10 kJ/mol. The understanding of cocrystal explosive was deepened and the further application was promoted.

Keywords: Cocrystals; Kinetics of decomposition; Phase transition.