Stabilities and defect-mediated lithium-ion conduction in a ground state cubic Li3 N structure
- Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy
- North Dakota State Univ., Fargo, ND (United States). Center for Computationally Assisted Science and Technology
- Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronom
A stable ground state structure with cubic symmetry of Li3N (c-Li3N) is found by ab initio initially symmetric random-generated crystal structure search method. Gibbs free energy, calculated within quasi-harmonic approximation, shows that c-Li3N is the ground state structure for a wide range of temperature. The c-Li3N structure has a negative thermal expansion coefficient at temperatures lower than room temperature, due mainly to two transverse acoustic phonon modes. This c-Li3N phase is a semiconductor with an indirect band gap of 1.90 eV within hybrid density functional calculation. We also investigate the migration and energetics of native point defects in c-Li3N, including lithium and nitrogen vacancies, interstitials, and anti-site defects. Lithium interstitials are found to have a very low migration barrier (~0.12 eV) and the lowest formation energy among all possible defects. Thus, the ionic conduction in c-Li3N is expected to occur via an interstitial mechanism, in contrast to that in the well-known α-Li3N phase which occurs via a vacancy mechanism.
- Research Organization:
- Ames Lab., Ames, IA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- AC02-07CH11358; SC0001717
- OSTI ID:
- 1249339
- Report Number(s):
- IS-J-8948; PPCPFQ
- Journal Information:
- Physical Chemistry Chemical Physics. PCCP (Print), Vol. 18, Issue 5; ISSN 1463-9076
- Publisher:
- Royal Society of ChemistryCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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