title: Stabilization of metastable ferroelectric Ba₁-xCaxTi₂O₅ by breaking Ca-site selectivity via crystallization from glass.
abstract: The thermal stability and dielectric and structural properties of ferroelectric Ba1-xCaxTi2O5 (0 ≤ x ≤ 0.30) prepared by crystallization from glass are investigated. The Ba1-xCaxTi2O5 compounds with x < 0.10 are thermally stable phases, while those with x ≥ 0.10 are metastable phases. The ferroelectric transition temperature drastically decreases from 470 to 220°C with increasing x. Crystal structure analyses reveal that one of two possible Ba sites is occupied by Ca in the stable phase region, while Ca-site selectivity is broken in the metastable phase region. The Ca-site selectivity introduces local distortion and makes the crystal lattice unstable. However, the local distortion is suppressed by the occupancy of Ca into both Ba sites. Accordingly, the metastable ferroelectric phase can be obtained beyond the substitution limit of Ca by crystallization from the glassy state. The stabilization mechanism provides possible wide control of the functionality of materials by expanding the composition range.
authors.affiliation: Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan.
authors.forename: Atsunobu
authors.initials: A
authors.lastname: Masuno
authors.forename: Chikako
authors.initials: C
authors.lastname: Moriyoshi
authors.forename: Teruyasu
authors.initials: T
authors.lastname: Mizoguchi
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Okajima
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kuroiwa
authors.forename: Yasutomo
authors.initials: Y
authors.lastname: Arai
authors.forename: Jianding
authors.initials: J
authors.lastname: Yu
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Inoue
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Watanabe