Actinium Hydrides AcH10, AcH12, and AcH16 as High-Temperature Conventional Superconductors

Dmitrii V Semenok; Alexander G Kvashnin; Ivan A Kruglov; Artem R Oganov

doi:10.1021/acs.jpclett.8b00615

Actinium Hydrides AcH₁₀, AcH₁₂, and AcH₁₆ as High-Temperature Conventional Superconductors

J Phys Chem Lett. 2018 Apr 19;9(8):1920-1926. doi: 10.1021/acs.jpclett.8b00615. Epub 2018 Apr 3.

Authors

Dmitrii V Semenok^{1

2}, Alexander G Kvashnin^{1

2}, Ivan A Kruglov^{2

3}, Artem R Oganov^{1

2

3

4}

Affiliations

¹ Skolkovo Innovation Center , Skolkovo Institute of Science and Technology , 3 Nobel Street , Moscow 143026 , Russian Federation.
² Moscow Institute of Physics and Technology , 9 Institutsky Lane , Dolgoprudny 141700 , Russian Federation.
³ Dukhov Research Institute of Automatics (VNIIA) , Moscow 127055 , Russian Federation.
⁴ International Center for Materials Discovery , Northwestern Polytechnical University , Xi'an 710072 , China.

PMID: 29589444
DOI: 10.1021/acs.jpclett.8b00615

Abstract

The stability of numerous unexpected actinium hydrides was predicted via the evolutionary algorithm USPEX. The electron-phonon interaction was investigated for the hydrogen-richest and most symmetric phases: R3̅ m-AcH₁₀, I4/ mmm-AcH₁₂, and P6̅ m2-AcH₁₆. Predicted structures of actinium hydrides are consistent with all previously studied Ac-H phases and demonstrate phonon-mediated high-temperature superconductivity with T_C in the range of 204-251 K for R3̅ m-AcH₁₀ at 200 GPa and 199-241 K for P6̅ m2-AcH₁₆ at 150 GPa, which was estimated by directly solving the Eliashberg equation. Actinium belongs to the series of d¹ elements (Sc-Y-La-Ac) that form high- T_C superconducting (HTSC) hydrides. Combining this observation with previous predictions of p⁰-HTSC hydrides (MgH₆ and CaH₆), we propose that p⁰ and d¹ metals with low-lying empty orbitals tend to form phonon-mediated HTSC metal polyhydrides.