A ferroelectric barium titanate, BaTi₂O₅

Abstract

The crystal structure of monobarium dititanium pentaoxide, BaTi(2)O(5), synthesized by a floating-zone method, was studied by X-ray diffraction. Previous reports describe the structure as being in the monoclinic centrosymmetric space group C2/m. We have recently found that this material exhibits ferroelectricity, and therefore BaTi(2)O(5) should have lower symmetry. The crystal structure of BaTi(2)O(5) was refined in space group C2, revealing a displacement of the Ti atoms along the b axis. This result is consistent with the fact that the ferroelectricity of BaTi(2)O(5) was only observed along the b axis.

Dielectric Properties of Poly- and Single-Crystalline BaTi<SUB>2</SUB>O<SUB>5</SUB>

“…The crystal structure of BT 2 can be drawn by the combination of corner-and edgeshared TiO 6 octahedrons. 24) The arrangement of TiO 6 octahedrons is highly anisotropic. The connection of TiO 6 octahedrons is rather staggered in the a-and c-directions, and is well ordered in the b-direction as depicted in Figs.…”

Order-disorder nature of ferroelectric BaTi2O5

“…The crystal grown in air shows a sharp dielectric anomaly reaching 30 000 at T c ϳ 479°C. Kimura et al 7 shows the displacement of Ti atoms in the one of the Ti sites is mainly responsible for the ferroelectricity. Furthermore, ferroelectricity of this single crystal was confirmed and explained using first-principle calculation.…”

Two new superstructures Ba4Ti5O10and Ba4Ti4O11in epitaxial barium titanate nanodomains determined by nanobeam electron diffraction and high-resolution transmission electron microscopy

“…BaTiO 3 has a cubic perovskite structure at temperatures above its ferroelectric Curie point (~130°C) [27] and a tetragonal structure at room temperature. A variety of structures or compounds associated with barium titanate (BTO) have been found so far including BaTi 4 O 9 [21], Ba 2 TiO 4 [5], BaTi 5 O 11 [31], Ba 6 Ti 17 O 40 [35], Ba 4 Ti 13 O 30 [32], BaTi 6 O 13 [33], BaTi 2 O 5 [8,18,34,41], Ba 2 Ti 9 O 20 [36], Ba 2 Ti 5 O 12 [17] and Ba 2 Ti 13 O 22 [1]. Some of these structures exhibit interesting ferroelectric or dielectric properties.…”