Phase transformation and ionic conductivity mechanism of a low-temperature sintering semiconductor Na2CaV4O12

Caige Liu, Shuangfeng Wu, Changzhi Yin, Jungu Xu*, Ying Xiong, Laijun Liu*, Jibran Khaliq, Chunchun Li*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)
33 Downloads (Pure)


Alkaline earth metal vanadates have drawn attention because of their potential applications in electrochemical devices. Here, Na2CaV4O12 was prepared at extremely low temperatures (350-550 oC) and showed a semiconductor behavior with a bandgap of 2.92 eV. A phase transition from P4/nbm to P
b2 occurred at 510 oC was identified by an in-situ XRD upon heating, where the 16 n site for oxygen atoms in the P4/nbm phase evolves into two distinguishable 8i sites in the P
b2 phase. Ionic conduction in Na2CaV4O12 at elevated temperatures was reported for the first time in the present work. A strong correlation between ionic conductivity and phase structure of Na2CaV4O12 is observed. The charged carriers are mainly sodium ions for the low-temperature P4/nbm phase, while mixed conduction contributed by sodium ions and oxide ions happened in the transformed phase. Bond valence-based energy landscape calculations disclosed a two-dimensional interstitial diffusion mechanism for Na+ ions in the Na2Ca-layers, as well as a two-dimensional diffusion mechanism for oxide ions in the V4O12-layers. The novel semiconductor ceramic would have potential applications in all-solid sodium ions batteries or solid oxide fuel cells as electrolytes.
Original languageEnglish
Article number161259
Number of pages6
JournalJournal of Alloys and Compounds
Early online date21 Jul 2021
Publication statusPublished - 15 Dec 2021


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