高压下CL-20拉曼光谱和红外光谱相变研究

为了更好地认识和了解CL-20晶体结构演变规律和相变行为,利用金刚石对顶砧超高压实验技术,在0~50GPa下,研究了高压下ε-CL-20的原位拉曼光谱和红外光谱。结果表明,CL-20晶体在整个加压过程中存在两个相变,第一个相变发生在4.2~7.5GPa,认为是ε相到对称性更低的γ相转变,相变产生的原因是在压强的作用下,笼环外的硝基方向发生改变,电子云密度重置导致的分子构型转变;第二个相变发生在14.2~18.9GPa,属于γ相到ζ相的晶体结构转变;卸压后,拉曼和红外光谱恢复常压状态,表明CL-20晶体在研究压强范围内的相变过程是可逆的。

Study on Raman and Infrared Spectroscopy of CL-20 Crystal Transition at High Pressure

To better understand the evolution law and phase transition behavior of CL-20 crystal structure,high pressure phase transition ofε-CL-20 was investigated in the range of 0-50GPa by in-situ Raman and infrared spectrum method in diamond anvil cell,respectively.The results show that there are two phase transitions in the CL-20 crystal during the whole pressurization process.The first transition starts at 4.2GPa and completes at about 7.5GPa,which is considered to be theγphase transition from theεphase to the lower symmetry.The reason of the phase transition is that the direction of nitro group outside the cage ring changes under the action of pressure,and the molecular configuration transition caused by the reset of electron cloud density.The second phase transition occurs at 14.2-18.9GPa,which belongs to the crystal structure transition fromγphase to theζphase.After pressure release,Raman and infrared spectra return to atmospheric pressure state,indicating that the phase transition process of the CL-20 crystal is reversible.