548 / 2019-03-20 13:01:09

Dehydrogenation through the pressure-induced polymerization processes of phosphine

hydrides, superconducivity, high pressure, high Tc

全体主题 > High Pressure Physics and Materials Science

Since superconducting mercury was first reported [2,3], scientists have never stopped searching for new high-Tc superconductors. PH3, a typical hydrogen-rich hydride, has attracted a great deal of research interest because of its superconducting transition at ~100K and ~200 GPa discovered by Drozdov et al [4]. In this talk, I am going to present our recent experimental results of PH3 using Raman, IR, and x-ray diffraction (XRD) measurements, as well as theoretical calculations, showing the pressure-induced dehydrogenation of phosphine at high pressure up to 205GPa. We found that PH3 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, P2H4 and P4H6, were verified experimentally and can be recovered to ambient pressure. Under further compression above 35 GPa, the P4H6 directly decomposed into elemental phosphorus. Low temperature can greatly hinder polymerization/decomposition under high pressure, and retain P4H6 up to at least 205 GPa. The superconductivity transition temperature of P4H6 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 P2H4 and P4H6 are the only stable P-H compounds between PH3 and elemental phosphorus, shedding light on the superconducting mechanism.

Reference
1. Ye Yuan, Yinwei Li, Guoyong Fang, Guangtao Liu, Cuiying Pei, Xin Li, Haiyan Zheng, Yuexiao Pan, Ke Yang, Lin Wang, arXiv:1706.01308.
2. H. K. Onnes, Proc. K. Akad. van Wet. Te Amsterdam 14, 113 (1911).
3. H. Onnes, KNAW Proc. 113 (1911).
4. A. P. Drozdov, M. I. Eremets, and I. a. Troyan, arXiv:1508.06224 1, 1 (2015).