High-pressure Phase Stability and Superconductivity of Pnictogen Hydrides and Chemical Trends for Compressed Hydrides

The recent breakthrough discovery of unprecedentedly high temperature superconductivity of 203 K in compressed sulfur hydrides has stimulated significant interest in finding new hydrogen-containing superconductors and elucidating the physical and chemical principles that govern these materials and their superconductivity. Here we report the prediction of high temperature superconductivity in the family of pnictogen hydrides using first principles calculations in combination with global optimization structure searching methods. The hitherto unknown high-pressure phase diagrams of binary hydrides formed by the pnictogens of phosphorus, arsenic and antimony are explored, stable structures are identified and their electronic, vibrational and superconducting properties are investigated. We predict that SbH_4 and AsH_8 are high-temperature superconductors at megabar pressures, with critical temperatures in excess of 100 K. The highly symmetrical hexagonal SbH_4 phase is predicted to be stabilized above about 150 GPa, which is readily achievable in diamond anvil cell experiments. We find that all phosphorus hydrides are metastable with respect to decomposition into the elements within the pressure range studied. Trends based on our results and data in the literature reveal a connection between the high-pressure behaviors and ambient-pressure chemical quantities which provides insight into understanding which elements may form hydrogen-rich high-temperature superconducting phases at high pressures.The authors thank Eva Zurek for sharing structure data for iodine hydride. The work at Jilin Univ. is supported by the funding of National Natural Science Foundation of China under Grant Nos. 11274136 and 11534003, 2012 Changjiang Scholar of Ministry of Education and the Postdoctoral Science Foundation of China under grant 2013M541283. L.Z. acknowledges funding support from the Recruitment Program of Global Youth Experts in China. Part of calculations was performed in the high performance computing center of Jilin Univ. R.J.N. acknowledges financial support from the Engineering and Physical Sciences Research Council (EPSRC) of the UK [EP/J017639/1]. R.J.N. and C.J.P. acknowledge use of the Archer facility of the U.K.’s national high-performance computing service (for which access was obtained via the UKCP consortium [EP/K013564/1]).This is the final version of the article. It first appeared from ACS via https://doi.org/10.1021/acs.chemmater.5b0463