Pressure-stabilized superconductive yttrium hydrides

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

doi:10.1038/srep09948

Pressure-stabilized superconductive yttrium hydrides

Sci Rep. 2015 May 5:5:9948. doi: 10.1038/srep09948.

Authors

Yinwei Li¹, Jian Hao², Hanyu Liu³, John S Tse³, Yanchao Wang⁴, Yanming Ma⁴

Affiliations

¹ 1] School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116, China [2] State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China [3] Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, S7N 5E2, Canada.
² School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116, China.
³ Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, S7N 5E2, Canada.
⁴ State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China.

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.