Pressure-stabilized superconductive yttrium hydrides.

Yinwei Li,Jian Hao,Yanming Ma,John S Tse,Yanchao Wang,Hanyu Liu

doi:10.1038/srep09948

Abstract

The search for high-temperature superconductors has been focused on compounds containing a large fraction of hydrogen, such as SiH4(H2)2, CaH6 and KH6. Through a systematic investigation of yttrium hydrides at different hydrogen contents using an structure prediction method based on the particle swarm optimization algorithm, we have predicted two new yttrium hydrides (YH4 andYH6), which are stable above 110 GPa. Three types of hydrogen species with increased H contents were found, monatomic H in YH3, monatomic H+molecular “H2” in YH4 and hexagonal “H6” unit in YH6. Interestingly, H atoms in YH6 form sodalite-like cage sublattice with centered Y atom. Electron-phonon calculations revealed the superconductive potential of YH4 and YH6 with estimated transition temperatures (Tc) of 84–95 K and 251–264 K at 120 GPa, respectively. These values are higher than the predicted maximal Tc of 40 K in YH3.

Highlights

The search for high-temperature superconductors has been focused on compounds containing a large fraction of hydrogen, such as SiH4(H2)[2], CaH6 and KH6
Through a systematic investigation of yttrium hydrides at different hydrogen contents using an structure prediction method based on the particle swarm optimization algorithm, we have predicted two new yttrium hydrides (YH4 andYH6), which are stable above 110 GPa
Theoretical studies have revealed a large number of superconducting hydrides (SiH42–4, SnH45,6, GeH47, ScH38, YH39, GaH310, H2S11 et al.) at high pressures with predicted Tc ranging from 17 to 86 K

Summary

Introduction

The search for high-temperature superconductors has been focused on compounds containing a large fraction of hydrogen, such as SiH4(H2)[2], CaH6 and KH6. Electronphonon calculations revealed the superconductive potential of YH4 and YH6 with estimated transition temperatures (Tc) of 84–95 K and 251–264 K at 120 GPa, respectively These values are higher than the predicted maximal Tc of 40 K in YH3. Theoretical studies have revealed a large number of superconducting hydrides (SiH42–4, SnH45,6, GeH47, ScH38, YH39, GaH310, H2S11 et al.) at high pressures with predicted Tc ranging from 17 to 86 K. A new type of hydrogen solvated molecular complex SiH4(H2)[2] has been synthesized[13,14] and was predicted to have a Tc of ~100 K at 250 GPa15, which is much higher than the 17 K observed in SiH42.The experimental and theoretical studies have led to further investigations on hydrides with large hydrogen fraction that may provide a pathway to better superconductors. Electron-phonon calculations show both YH4 and YH6 are superconductive with relatively high Tc

Methods

Results

Discussion

Conclusion