Theoretical and Experimental Studies of Gallate Melilite Electrides From Topotactic Reduction of Interstitial Oxide Ions

Lijia Zhou (1) , Jinxiao Zhang (1) , Congling Yin (1) , Luhui Meng (2) , Jiachen Li (1) , Yuexiang Li (2) , Franck Fayon (3) , Mathieu Allix (3) , Xiaojun Kuang (1)

1 Guilin University of Technology
2 Nanchang University
3 CEMHTI - Conditions Extrêmes et Matériaux : Haute Température et Irradiation

Non-stoichiometric La1.5Sr0.5Ga3O7.25 melilite oxide ion conductor features active interstitial oxygen defects in the pentagonal rings with high mobility. In this study, electron localization function calculation by density function theory indicated that the interstitial oxide ions located in the pentagonal rings of the gallate melilites may be removed and replaced by electron anions, which are confined within the pentagonal rings, which would therefore convert the melilite interstitial oxide ion conductor into a 0D electride. The more active interstitials oxide ions, compared to the framework oxide ions, make the La1.5Sr0.5Ga3O7.25 melilite structure more reducible by CaH2 using topotactic reduction, in contrast with the hardly reducible nature of the parent LaSrGa3O7. The topotactic reduction enhances the bulk electronic conduction by ~ one order of magnitude for La1.5Sr0.5Ga3O7.25. The oxygen loss in the melilite structure was verified and most likely takes place on the active interstitial oxide ions. The new identified confinement space for electronic anions in melilite interstitial oxide ion conductors presented here provides a new strategy to access inorganic electrides from interstitial oxide ion conductor electrolytes.

Mots clés: Electride; Nonstoichiometric Melilite; Interstitial oxide ions; Topotactic reduction

Domaines: Chimie inorganique; Matériaux

Lijia Zhou, Jinxiao Zhang, Congling Yin, Luhui Meng, Jiachen Li, et al.. Theoretical and Experimental Studies of Gallate Melilite Electrides From Topotactic Reduction of Interstitial Oxide Ions. Inorganic Chemistry, 2022, 61 (28), pp.10915-10924. ⟨10.1021/acs.inorgchem.2c01393⟩. ⟨hal-03874457⟩