- Title
- Anion ordering and vacancy defects in niobium perovskite oxynitrides
- Creator
- Brown, Joshua J.; Shao, Youxiang; Ke, Zhuofeng; Page, Alister J.
- Relation
- Materials Advances Vol. 2, Issue 7, p. 2398-2407
- Publisher Link
- http://dx.doi.org/10.1039/d1ma00122a
- Publisher
- Royal Society of Chemistry
- Resource Type
- journal article
- Date
- 2021
- Description
- Niobium perovskite oxynitrides are emerging as promising semiconductor materials for solar energy conversion processes, due to their physical properties and amenability to defect engineering. However, defect engineering in mixed-anion semiconductors such as perovskite oxynitrides is generally hindered by the absence of long-range order in the crystal lattice, a phenomenon known as anion-ordering. We demonstrate how anion ordering influences the stability and mobility of point defects in two exemplar perovskite oxynitrides, BaNbO2N and LaNbON2. Accurate first-principles calculations show that fully cis-anion orderings in BaNbO2N are more stable than fully trans-anion orderings, whereas anion orderings with mixed dimensionality may be more prevalent in the lower-symmetry LaNbON2. Anion ordering in LaNbON2 is also influenced by a pronounced A-site coordination sphere effect not observed in BaNbO2N, whereby local La-(O,N)12 coordination environments give rise to alternating LaO and LaN layers in the bulk material. Anion order was predicted to effect the redistribution of electrons upon anion vacancy creation to the cation sublattice. Diffusion barriers for O2- vacancies in trans-ordered BaNbO2N were found to be lower than those for N3- vacancies, suggesting that stabilising trans-ordered phases of BaNbO2N will yield more effective retention of nitrogen content in this material. The reverse is the case for LaNbON2, with N3- vacancy defects exhibiting more facile diffusion than O2- vacancy defects. We believe these insights will aid the emergent understanding of defect engineering in mixed-anion perovskite oxynitride semiconductors, and specifically help facilitate strategies for stabilising their nitrogen content.
- Subject
- Anion; niobium perovskite oxynitrides; vacancy defects; defect engineering
- Identifier
- http://hdl.handle.net/1959.13/1431977
- Identifier
- uon:39005
- Identifier
- ISSN:2633-5409
- Rights
- This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence, http://creativecommons.org/licenses/by-nc/3.0/.
- Language
- eng
- Full Text
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