Characteristic mechanism for fast H conduction in LaH2.5O0.25

Albert Iskandarov, Tomofumi Tada, Soshi Iimura, Hideo Hosono

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

Solid hydrides are a new class of ionic conductors promising for future applications for hydrogen-carrier, catalysis, and energy conversion. The record-high H conductivity reported for LaH2.5O0.25 is caused by extraordinarily large pre-exponential factor, which cannot be justified within any simple diffusion picture. To reveal H dynamics in LaH2.5O0.25 on atomistic level, we developed DFT-based neural-network-potential for large-scale molecular dynamics (MD) simulation and discovered the H diffusion mechanism: the stoichiometric vacancies are ordered and almost immobile, but they can be rarely kicked-out and become fast mobile vacancies that migrate in a coupled manner with 3H ring-like rotations. The MD and DFT phonon analysis reveal that the mobile vacancy formation gives rise to an extremely large entropy leading to the anomalously large pre-exponential factor, and that the anharmonicity of H vibrations causes the large pre-exponential factor. A design concept for faster H conductor is proposed based on the present finding.

Original languageEnglish
Article number117825
JournalActa Materialia
Volume230
DOIs
Publication statusPublished - May 15 2022

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

Fingerprint

Dive into the research topics of 'Characteristic mechanism for fast H conduction in LaH2.5O0.25'. Together they form a unique fingerprint.

Cite this