Details

Autor(en) / Beteiligte

• Yang, Lihua
• Zhang, Yukai
• Chen, Yanli
• Zhong, Xin
• Wang, Dandan
• Lang, Jihui
• Qu, Xin
• Yang, Jinghai

Titel

Unconventional Stoichiometries of Na-O Compounds at High Pressures

Ist Teil von

• Materials, 2021-12, Vol.14 (24), p.7650

Ort / Verlag

Switzerland: MDPI AG

Erscheinungsjahr

2021

Link zum Volltext

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• It has been realized that the stoichiometries of compounds may change under high pressure, which is crucial in the discovery of novel materials. This work uses systematic structure exploration and first-principles calculations to consider the stability of different stoichiometries of Na-O compounds with respect to pressure and, thus, construct a high-pressure stability field and convex hull diagram. Four previously unknown stoichiometries (NaO , NaO , Na O, and Na O) are predicted to be thermodynamically stable. Four new phases ( 2 and 2 NaO and and 2 NaO ) of known stoichiometries are also found. The O-rich stoichiometries show the remarkable features of all the O atoms existing as quasimolecular O units and being metallic. Calculations of the O-O bond lengths and Bader charges are used to explore the electronic properties and chemical bonding of the O-rich compounds. The Na-rich compounds stabilized at extreme pressures (P > 200 GPa) are electrides with strong interstitial electron localization. The 2 phase of Na O is found to be a zero-dimensional electride with an insulating character. The phase of Na O is a one-dimensional metallic electride. These findings of new compounds with unusual chemistry might stimulate future experimental and theoretical investigations.