Jin Cheng, Liu Ying, Wang Lijuan, Zhang Weijing, Zhang Tonglai, Zhu Jinlong
Center for High Pressure Science and Technology Advanced Research (HPSTAR) Beijing 100094 China
Xi'an Modern Chemistry Research Institute Xi'an 710065 China.
RSC Adv. 2020 Aug 14;10(50):30069-30076. doi: 10.1039/d0ra06328b. eCollection 2020 Aug 10.
Nitrogen-rich energetic materials have attracted certain interest as promising high energy density materials (HEDMs) in recent years. Pure N and nitrogen-based molecular crystals are ideal HEDMs that would polymerize under high pressure, as reported in previous literature. We selected a 1,5-diamino-1-tetrazole (DAT) crystal, which has two kinds of molecular structures and hydrogen bonds, to study under high pressure by spectroscopy and diffraction due to its high nitrogen percentage and low sensitivities. Pressure-induced structure transitions occur at pressures of 2.3-6.6 GPa, ∼8.5 GPa, and ∼17.7 GPa. The phase transition at 2.3-6.6 GPa is related to the rotation of NH, and the latter two transitions are caused by both the rotation of NH and the distortion of the heterocycle. Significantly, the reconstitution of the hydrogen bond may induce the rotation/distortion of the NH/heterocycle in the second phase transition. There is no evidence showing a transformation between the two molecular structures in the whole pressure range studied. Our investigation uncovers the phase transition mechanism of DAT under pressure, which will help to find targeted HEDMs.
近年来，富氮含能材料作为有前景的高能量密度材料（HEDMs）引起了一定的关注。如先前文献报道，纯氮和氮基分子晶体是理想的高能量密度材料，在高压下会发生聚合。我们选择了具有两种分子结构和氢键的1,5 - 二氨基 - 1 - 四唑（DAT）晶体，因其高氮含量和低感度，通过光谱学和衍射手段对其进行高压研究。压力诱导的结构转变发生在2.3 - 6.6 GPa、约8.5 GPa和约17.7 GPa的压力下。2.3 - 6.6 GPa的相变与NH的旋转有关，后两个转变是由NH的旋转和杂环的畸变共同引起的。值得注意的是，氢键的重构可能在第二次相变中诱导NH/杂环的旋转/畸变。在所研究的整个压力范围内，没有证据表明两种分子结构之间存在转变。我们的研究揭示了DAT在压力下的相变机制，这将有助于找到有针对性的高能量密度材料。
