Ferroelectric and photocatalytic properties of Aurivillius phase Ca₂Bi₄Ti₅O₁₈

Abstract

Aurivillius phase Ca 2 Bi 4 Ti 5 O 18 powders with micrometer size were produced by solid-state reaction. X-ray diffraction revealed that the powders had polar orthorhombic structure with space group of B2cb. Ca 2 Bi 4 Ti 5 O 18 ceramic exhibited frequency independent dielectric anomaly at 774°C. The piezoelectric coefficient d 33 value of poled Ca 2 Bi 4 Ti 5 O 18 pellets was 0.7 ± 0.2 pC/N. Both frequency independent dielectric anomaly and detectable d 33 value clearly indicated that Ca 2 Bi 4 Ti 5 O 18 is a ferroelectric material with Curie point of 774 ℃. UV-vis absorption spectra revealed that Ca 2 Bi 4 Ti 5 O 18 had a direct band gap of 3.2 eV. Photocatalytic activity of the Ca 2 Bi 4 Ti 5 O 18 powders was examined by degradation of rhodamine B (RhB) under simulated solar light. 16% of RhB solution was degraded by Ca 2 Bi 4 Ti 5 O 18 powders after 4 hours UV-vis irradiation. With Ag nanoparticles deposited on the Ca 2 Bi 4 Ti 5 O 18 powders surface, 50% of RhB was degraded under the same irradiation condition. The fitted degradation rate constant of Ag decorated Ca 2 Bi 4 Ti 5 O 18 was 4 times higher than that of bare Ca 2 Bi 4 Ti 5 O 18. This work suggested that the Aurivillius ferroelectric Ca 2 Bi 4 Ti 5 O 18 is a promising candidate for photocatalytic applications.

Polar materials for photocatalytic applications: A critical review

“…(G) Reproduced with permission. [ 134 ] Copyright 2020, American Ceramic Society. (H) Reproduced with permission.…”

“…Figure 12F reveals that introducing radical scavengers reduces RhB dye degradation, with triethanolamine (TEOA) having a more substantial inhibitory effect than benzoquinone (BQ) and isopropyl alcohol (IPA), highlighting the primary role of the h + radical in RhB degradation. Figure 12G indicates that Ca 2 Bi 4 Ti 5 O 18 powders degraded 16% of RhB under simulated solar light in 4 h, [ 134 ] but silver modification increased this rate, achieving 50% degradation. Bi 2 WO 6 transforms from 3D flowerlike to 2D platelike forms in a pH‐controlled, surfactant‐free method, altering its photocatalytic activity in RhB degradation.…”

Aurivillius Oxides Nanosheets-Based Photocatalysts for Efficient Oxidation of Malachite Green Dye

“…In contrast to the pure perovskite structure, in pseudo-perovskite materials the disposition of the octahedra is distorted. In the last years, Aurivillius phase oxides, originally discovered in 1949 [36], have gained much interest [37,38]. These are layered metal oxides, generally formulated as Bi 2 A m−1 B m O 3m+3 where A and B are transition metals, O oxygen and m a positive integer whose value depends on the specific elements involved and the phase structure.…”

“…In this work we apply Mo and W (separately) as component B (Scheme 1A) with condition m = 1 such that component A is not present. Aurivillius phases are generally known as oxides in literature [38][39][40][41] and commonly referred to as compounds containing bismuth as a cation, even though they are covalent solids (in the same way that bismuth vanadate, bismuth tungstate are covalent solids) [42]. Bismuth-containing photocatalysts are recurring in literature as standalone or base materials for composite photocatalysts [28,43].…”

“…However, due to the weak strength of the halogen bond [44], bismuth oxyhalides are fairly sensitive (except BiOBr) to photoinduced corrosion. Aurivillius phases are ferroelectric, that is, they have a permanent electric polarization between the layers, thanks to their particular structure [38,45]. Alternate layers in these materials behave as a two-dimensional capacitor.…”