The Systematic Study on the Stability and Superconductivity of Y‐Mg‐H Compounds under High Pressure
Abstract
Structural stabilities of high‐pressure YMgHxphases (, and 16) and their superconductivities are investigated by employing evolutionary‐algorithm‐based crystal search combined with first‐principles calculations. For predicted candidate structures of YMgHx, the convex hull and phonon analyses reveal seven stable and two metastable phases. For all the predicted phases, superconducting transition temperatures (Tc) are also predicted by using the McMillan formula. ‐YMgH6is found having K at 300 GPa comparable to the boiling temperature of liquid nitrogen, and high‐Tc(≥77 K) being predicted for the H‐richer phases, ‐YMgH8(124 K at 300 GPa), ‐YMgH12(152 K at 250 GPa), and ‐YMgH12(190 K at 200 GPa), which possess clathrate structures composed of H14, H18, H24, and H24cages, respectively. To elucidate why the H‐rich phases attain high‐Tc, electronic and phonon band structures as well as electron–phonon coupling strength are analyzed based on Eliashberg spectral functions. The clathrate structures exhibit both a larger H‐driven electronic density of states at the Fermi level and a denser H‐driven phonon density of states, correlating with larger EPC constants. These structural and chemical bonding analyses reveal that the highest‐Tcphase ‐YMgH12has H4units formed in the sodalite cage.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jan 18, 2022
- Source ID
- 10.1002/adts.202100364
Entities
People
- Kenta Hongo
- Kousuke Nakano
- Pedro Baptista De Castro
- Peng Song
- Ryo Maezono
- Yoshihiko Takano
- Zhufeng Hou
Organizations
- Air Force Office of Scientific Research
- International School for Advanced Studies
- Japan Advanced Institute of Science and Technology
- National Institute for Materials Science
- University of Tsukuba