高压下ZnSe 纳米带的结构相变及拉曼散射研究

 利用高压原位角散X射线衍射实验研究了ZnSe纳米带的结构稳定性。发现样品在12.6 GPa 附近存在一个从立方闪锌矿型到立方岩盐矿型的结构相变，并且在相变点附近存在较大的体积收缩，相对体积变化率达13%。利用Birch-Murnaghan 状态方程拟合，得到了闪锌矿相的体弹模量约为56 GPa，略低于体材料的体弹模量（约67 GPa）；并得到其立方岩盐矿相的体弹模量约为116 GPa。高压拉曼散射实验结果表明，横光学声子模散射峰在5.5 GPa压力附近发生劈裂，纵光学声子模散射峰在12.8 GPa压力以上逐渐消失。根据角散实验的体弹模量数据，计算得到了闪锌矿相中对应不同声子模式的格林爱森常数。

Structural Transition and Raman Scattering of ZnSe Nanoribbons under High Pressure

Structural stability of ZnSe nanoribbons was analyzed by means of high pressure in situ angular dispersive X-ray diffraction(ADXD). The pressure induced structural transition from the Zinc blende (ZB) to a rocksalt (RS) phase occurs at about 12.6 GPa, and at the transition point the relative volume reduction is close to 13%. By fitting the relative volume-pressure relation to the Birch-Murnaghan equation of states, the bulk modulus B₀ for the ZB and RS phases were determined. The values of B₀ are 56 GPa (B′₀=4) and 116 GPa (B′₀=4) for the former and the latter, respectively. According to the measured high-pressure Raman scattering spectra, the TO phonon modes split into two peaks at about 5.5 GPa, and the LO peak gradually disappears above 12.8 GPa due to the semiconductor-metal transition. Using the value of the bulk modulus obtained from the ADXD experiments, the corresponding mode Grüneisen parameters are obtained for the ZB phase.