Structural Behavior of the Four-Layer Aurivillius-Phase Ferroelectrics SrBi4Ti4O15 and Bi5Ti3FeO15

Unusual High‐Temperature Structural Behaviour in Ferroelectric Bi2WO6

“…[12,13] Secondly, a continuous transition from polar orthorhombic to centrosymmetric orthorhombic at T C , followed by a second transition to centrosymmetric tetragonal above T C ; this corresponds to successive freezing out of two different octahedral tilt modes, and has been observed in SrBi 2 Ta 2 O 9 and related compositions, [14,15] and SrBi 4 Ti 4 O 15 . [16] Finally, an apparently direct transition from polar orthorhombic to centrosymmetric tetragonal at T C ; this type of transition is required to be firstorder by group theory and is still the subject of some controversy. [17,18] Crystal structure of the HT phase: In the earlier work of Watanabe [6] it was postulated that the crystal structure of HT-Bi 2 WO 6 was isomorphous to that of the ambient-temperature structure of the lanthanide-doped derivatives Bi 2Àx Ln x -WO 6 (approximate composition limits 0.3 < x < 1.3 for most lanthanides).…”

Structure and ferroelectric property of Nb-doped SrBi4Ti4O15 ceramics

“…BLSF has potential use in device application because of their relative high Curie temperature, high dielectric breakdown strength, low dielectric loss, and high anisotropy. SBT, which contain four perovskite-like TiO 6 octahedron units stacked in between (Bi 2 O 2 ) 2+ layers, has orthorhombic symmetry with space group A21am C 12 2v À Á a ¼ 5:4280; b ¼ 5:4380; c ¼ 40:9400) [4] (Fig. 1).…”

Octahedral tilting, domain structure and piezoelectricity in perovskites and related ceramics

“…The intermediate phases were considered to be distorted to orthorhombic as a result of octahedral rotations but para-rather than ferroelectric. In later work, Hervoches et al [32,33] and Zhou et al [34] confirmed using X-ray and neutron diffraction the presence of these intermediate compounds with Amam symmetry in several Aurivillius phases with the characteristics initially suggested by Reaney et al [31] based on in-situ electron diffraction. Figure 7a and Figure 6a shows a typical distribution of maxima common- [6] ly observed with bismuth titanate-based materials.…”

“…In effect, the higher temperature ferroelastic domains become the ferroelectric non-180°domains [35]. Hervoches et al [32,33] and Zhou et al [34] have confirmed this phase transition sequence in several common Aurivillius phases.…”