Ferroelectric and antiferroelectric distortions coupling of nitride perovskite LaWN₃ under epitaxial strain using first-principles calculations

¹ Department of Information Engineering, Quzhou College of Technology - Quzhou 324000, China
² Frontier Institute of Science and Technology, and State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University - Xi'an 710049, China
³ Science and Technology on Electronic Test and Measurement Laboratory, North University of China Taiyuan 030051, China
⁴ Applied Physics, Luleå University of Technology - Luleå SE-97187, Sweden

^(a) E-mail: wangxiangjian@stu.xjtu.edu.cn (corresponding author)
^(b) E-mail: xlou03@mail.xjtu.edu.cn

Received: 12 May 2022
Accepted: 18 November 2022

Abstract

LaWN₃, a novel nitride perovskite, have been synthesized and its piezoelectric properties have been investigated (Talley K. R. et al., Science, 374 (2021) 1488). However, the understanding of its ferroelectric properties under the external strain is still lacking. Here, the misfit-strain–dependent coupling between antiferrodistortions (AFD) and ferroelectric (FE) distortions has been studied by using a first-principle approach. It can be observed that AFD and FE distortions can work cooperatively with each other as the compressive strain increases, and the coupling energy between them is found to work in different ways under various strains. Our results show that the coupling tends to stabilize the ground structure when the compressive strain is smaller than −1.9%, it works oppositely when the compressive strain becomes larger than 1.9%. Our results can provide us with more hints about the influence of the epitaxial strains on the intrinsic coupling behavior in the perovskite ferroelectric compounds, which is very important for us to design and fabricate new kinds of functional materials.