First-principles investigation on anion order, electronic structure and dielectric properties of BaTaO2N†
Abstract
Perovskite-type metal oxynitrides are emerging functional materials with tunable photocatalytic, dielectric and magnetic properties that may depend not only on the compositions but also on the distribution of oxygen and nitrogen ions. In this paper we use BaTaO2N as a representative to investigate the short-range order of the O/N distribution based on first-principles calculations and the cluster expansion model based Monte Carlo simulations. The impact of lattice vibration on short-range order is also considered by using the cluster expansion of the free energy. Strong short-range order is found to exist in BaTaO2N based on calculated cluster correlation functions, suggesting a strongly preferred cis configuration of the octahedron of Ta-(O4N2) with nearly random connection between octahedra. Special quasi-ordered structure is then constructed based on such anion ordering as a representative structure of BaTaO2N to perform further first-principles calculations of electronic and dielectric properties. Our work showcases a general approach to investigate chemical ordering of O/N distribution and its influences on physical properties of perovskite oxynitrides based on first-principles calculations.
- This article is part of the themed collection: 2019 Journal of Materials Chemistry A HOT Papers