title: Strain Engineering for Anion Arrangement in Perovskite Oxynitrides.
abstract: Mixed-anion perovskites such as oxynitrides, oxyfluorides, and oxyhydrides have flexibility in their anion arrangements, which potentially enables functional material design based on coordination chemistry. However, difficulty in the control of the anion arrangement has prevented the realization of this concept. In this study, we demonstrate strain engineering of the anion arrangement in epitaxial thin films of the Ca1-xSrxTaO2N perovskite oxynitrides. Under compressive epitaxial strain, the axial sites in TaO4N2octahedra tend to be occupied by nitrogen rather than oxygen, which was revealed by N and O K-edge linearly polarized X-ray absorption near-edge structure (LP-XANES) and scanning transmission electron microscopy combined with electron energy loss spectroscopy. Furthermore, detailed analysis of the LP-XANES indicated that the high occupancy of nitrogen at the axial sites is due to the partial formation of a metastable trans-type anion configuration. These results are expected to serve as a guide for the material design of mixed-anion compounds based on their anion arrangements.
authors.affiliation: Department of Chemistry, School of Science, The University of Tokyo , 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan.|Department of Chemistry, Graduate School of Science, Tohoku University , 6-3 Aramaki Aza Aoba, Aoba, Sendai, Miyagi 980-8578, Japan.
authors.forename: Daichi
authors.identifier: 0000-0003-2747-9675
authors.initials: D
authors.lastname: Oka
authors.affiliation: Department of Chemistry, School of Science, The University of Tokyo , 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan.|Kanagawa Academy of Science and Technology (KAST) , 3-2-1 Sakado, Takatsu, Kawasaki, Kanagawa 213-0012, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Hirose
authors.affiliation: Graduate School of Materials Science, Nara Institute of Science and Technology , Ikoma, Nara 630-0192, Japan.
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Matsui
authors.affiliation: Department of Chemistry, School of Science, The University of Tokyo , 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan.
authors.forename: Hideyuki
authors.identifier: 0000-0002-2398-4650
authors.initials: H
authors.lastname: Kamisaka
authors.affiliation: Institute of Scientific and Industrial Research, Osaka University , Ibaraki, Osaka 567-0047, Japan.
authors.forename: Tamio
authors.initials: T
authors.lastname: Oguchi
authors.affiliation: Graduate School of Materials Science, Nara Institute of Science and Technology , Ikoma, Nara 630-0192, Japan.
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Maejima
authors.affiliation: Graduate School of Materials Science, Nara Institute of Science and Technology , Ikoma, Nara 630-0192, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nishikawa
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI) , Kouto 1-1-1, Sayo, Hyogo 679-5198, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Muro
authors.forename: Kouichi
authors.initials: K
authors.lastname: Hayashi
authors.affiliation: Department of Chemistry, School of Science, The University of Tokyo , 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan.|Kanagawa Academy of Science and Technology (KAST) , 3-2-1 Sakado, Takatsu, Kawasaki, Kanagawa 213-0012, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Hasegawa
keywords: X-ray absorption near-edge structure; coordination chemistry; epitaxial thin film; oxynitride; perovskite; strain engineering