title: Enhancement of tetragonal anisotropy and stabilisation of the tetragonal phase by Bi/Mn-double-doping in BaTiO3ferroelectric ceramics.
abstract: To stabilise ferroelectric-tetragonal phase of BaTiO3, the double-doping of Bi and Mn up to 0.5 mol% was studied. Upon increasing the Bi content in BaTiO3:Mn:Bi, the tetragonal crystal-lattice-constants a and c shrank and elongated, respectively, resulting in an enhancement of tetragonal anisotropy, and the temperature-range of the ferroelectric tetragonal phase expanded. X-ray absorption fine structure measurements confirmed that Bi and Mn were located at the A(Ba)-site and B(Ti)-site, respectively, and Bi was markedly displaced from the centrosymmetric position in the BiO12cluster. This A-site substitution of Bi also caused fluctuations of B-site atoms. Magnetic susceptibility measurements revealed a change in the Mn valence from +4 to +3 upon addition of the same molar amount of Bi as Mn, probably resulting from a compensating behaviour of the Mn at Ti4+sites for donor doping of Bi3+into the Ba2+site. Because addition of La3+instead of Bi3+showed neither the enhancement of the tetragonal anisotropy nor the stabilisation of the tetragonal phase, these phenomena in BaTiO3:Mn:Bi were not caused by the Jahn-Teller effect of Mn3+in the MnO6octahedron, but caused by the Bi-displacement, probably resulting from the effect of the 6 s lone-pair electrons in Bi3+.
authors.affiliation: R&D Headquarters, Canon Inc., Ohta, Tokyo 146-8501, Japan.
authors.forename: Hisato
authors.initials: H
authors.lastname: Yabuta
authors.affiliation: R&D Headquarters, Canon Inc., Ohta, Tokyo 146-8501, Japan.
authors.forename: Hidenori
authors.initials: H
authors.lastname: Tanaka
authors.affiliation: R&D Headquarters, Canon Inc., Ohta, Tokyo 146-8501, Japan.
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Furuta
authors.affiliation: R&D Headquarters, Canon Inc., Ohta, Tokyo 146-8501, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Watanabe
authors.affiliation: R&D Headquarters, Canon Inc., Ohta, Tokyo 146-8501, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Kubota
authors.affiliation: R&D Headquarters, Canon Inc., Ohta, Tokyo 146-8501, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Matsuda
authors.affiliation: R&D Headquarters, Canon Inc., Ohta, Tokyo 146-8501, Japan.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Ifuku
authors.affiliation: Reaction Dynamics Research Center, Japan Atomic Energy Agency (JAEA), Sayo-cho, Hyogo 679-5148, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Yoneda