Yuan Ye, Li Yinwei, Fang Guoyong, Liu Guangtao, Pei Cuiying, Li Xin, Zheng Haiyan, Yang Ke, Wang Lin
Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China.
School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116, China.
Natl Sci Rev. 2019 May;6(3):524-531. doi: 10.1093/nsr/nwz010. Epub 2019 Jan 22.
The superconductivity of hydrides under high pressure has attracted a great deal of attention since the recent observation of the superconducting transition at 203 K in strongly compressed HS. It has been realized that the stoichiometry of hydrides might change under high pressure, which is crucial in understanding the superconducting mechanism. In this study, PH was studied to understand its superconducting transition and stoichiometry under high pressure using Raman, IR and X-ray diffraction measurements, as well as theoretical calculations. PH is stable below 11.7 GPa and then it starts to dehydrogenate through two dimerization processes at room temperature and pressures up to 25 GPa. Two resulting phosphorus hydrides, PH and PH, were verified experimentally and can be recovered to ambient pressure. Under further compression above 35 GPa, the PH directly decomposed into elemental phosphorus. Low temperature can greatly hinder polymerization/decomposition under high pressure and retains PH up to at least 205 GPa. The superconductivity transition temperature of PH is predicted to be 67 K at 200 GPa, which agrees with the reported result, suggesting that it might be responsible for superconductivity at higher pressures. Our results clearly show that PH and PH are the only stable P-H compounds between PH and elemental phosphorus, which is helpful for shedding light on the superconducting mechanism.
自从最近在强压缩的硫化氢中观察到203K的超导转变以来，高压下氢化物的超导性引起了广泛关注。人们已经认识到，氢化物的化学计量在高压下可能会发生变化，这对于理解超导机制至关重要。在本研究中，利用拉曼光谱、红外光谱和X射线衍射测量以及理论计算，对磷化氢进行了研究，以了解其在高压下的超导转变和化学计量。磷化氢在11.7GPa以下是稳定的，然后在室温及高达25GPa的压力下通过两个二聚化过程开始脱氢。实验验证了生成的两种磷化氢，即PH和PH，并可将其恢复到常压。在高于35GPa的进一步压缩下，PH直接分解为元素磷。低温可极大地阻碍高压下的聚合/分解，并使PH至少在205GPa下保持稳定。预测磷化氢在200GPa时的超导转变温度为67K，这与报道的结果一致，表明它可能是高压下超导性的原因。我们的结果清楚地表明，PH和PH是磷化氢与元素磷之间仅有的稳定的磷氢化合物，这有助于阐明超导机制。
