Pressure-induced superconductivity in the hydrogen-rich pseudobinary CaB - H n compounds
- Qingdao Univ., Shandong (China)
- Qingdao Univ., Shandong (China); Jilin Univ. (China)
- Ames Lab., and Iowa State Univ., Ames, IA (United States)
Here, the crystal structures of CaB – Hn compounds with n = 1 – 12 in a pressure range of 50–300 GPa were studied using the genetic algorithm method and first-principles density-function theory calculations. Stable structures with stoichiometry of CaB H6 and CaB H7 were predicted in different pressure range. BH4, BH5, and BH6 units were found to be the main motifs in these compounds. Moreover, metastable Imm2 CaB H7 is dynamically stable above 180 GPa, with the formation of tetrahedral BH4 unit surrounded by Ca atom and H3 unit. Electron-phonon coupling (EPC) calculations reveal that the superconducting properties are closely related to the strong hydrogen-boron bonding of the BH4 unit in Imm2, and Tc can reach ~200 K at 200 GPa. As the major units, BH4, BH5, and BH6 units exist in the Imm2, P2, and P21/m phases of CaB H7 at 300 GPa, respectively; the corresponding EPC parameter λ decreases with the increase of hydrogen content in CaB H7.
- Research Organization:
- Ames Lab., Ames, IA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division; National Natural Science Foundation of China (NSFC); Natural Science Foundation of Shandong Province; Higher Educational Science and Technology Program of Shandong Province of China
- Grant/Contract Number:
- AC02-07CH11358
- OSTI ID:
- 1875279
- Report Number(s):
- IS-J 10,656; 21773132; 12004210; 21603114; ZR2020MB046; J17KA179; TRN: US2307184
- Journal Information:
- Physical Review. B, Vol. 104, Issue 17; ISSN 2469-9950
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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