title: Pressure-driven formation and stabilization of superconductive chromium hydrides.
abstract: Chromium hydride is a prototype stoichiometric transition metal hydride. The phase diagram of Cr-H system at high pressures remains largely unexplored due to the challenges in dealing with the high activation barriers and complications in handing hydrogen under pressure. We have performed an extensive structural study on Cr-H system at pressure range 0 ∼ 300 GPa using an unbiased structure prediction method based on evolutionary algorithm. Upon compression, a number of hydrides are predicted to become stable in the excess hydrogen environment and these have compositions of Cr2Hn (n = 2-4, 6, 8, 16). Cr2H3, CrH2 and Cr2H5 structures are versions of the perfect anti-NiAs-type CrH with ordered tetrahedral interstitial sites filled by H atoms. CrH3 and CrH4 exhibit host-guest structural characteristics. In CrH8, H2 units are also identified. Our study unravels that CrH is a superconductor at atmospheric pressure with an estimated transition temperature (T c) of 10.6 K, and superconductivity in CrH3 is enhanced by the metallic hydrogen sublattice with T c of 37.1 K at 81 GPa, very similar to the extensively studied MgB2.
authors.affiliation: Science and Technology on Thermostructural Composite Materials Laboratory, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, PR China.|International Center for Materials Discovery, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, PR China.
authors.forename: Shuyin
authors.initials: S
authors.lastname: Yu
authors.affiliation: Science and Technology on Thermostructural Composite Materials Laboratory, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, PR China.
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Jia
authors.affiliation: IC2MP UMR 7285, Université de Poitiers-CNRS, 4, rue Michel Brunet TSA 51106-86073 Poitiers Cedex 9, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Frapper
authors.affiliation: Science and Technology on Thermostructural Composite Materials Laboratory, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, PR China.|International Center for Materials Discovery, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, PR China.
authors.forename: Duan
authors.initials: D
authors.lastname: Li
authors.affiliation: International Center for Materials Discovery, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, PR China.|Skolkovo Institute of Science and Technology, 5 Nobel Street, Skolkovo 143025, Russia.|Department of Geosciences, Center for Materials by Design, and Institute for Advanced Computational Science, State University of New York, Stony Brook, NY 11794-2100, USA.|Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region 141700, Russia.
authors.forename: Artem R
authors.initials: AR
authors.lastname: Oganov
authors.affiliation: Science and Technology on Thermostructural Composite Materials Laboratory, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, PR China.|International Center for Materials Discovery, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, PR China.
authors.forename: Qingfeng
authors.initials: Q
authors.lastname: Zeng
authors.affiliation: Science and Technology on Thermostructural Composite Materials Laboratory, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, PR China.
authors.forename: Litong
authors.initials: L
authors.lastname: Zhang