Ferroelectric and photocatalytic properties of Aurivillius phase Ca ₂ Bi ₄ Ti ₅ O ₁₈

Abstract

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 B 2 cb . 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.