Ferroelectric and photocatalytic properties of Aurivillius phase Ca2Bi4Ti5O18

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 ofB2cb. Ca(2)Bi(4)Ti(5)O(18)ceramic exhibited frequency independent dielectric anomaly at 774 degrees C. The piezoelectric coefficientd(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 detectabled(33)value clearly indicated that Ca(2)Bi(4)Ti(5)O(18)is a ferroelectric material with Curie point of 774 celcius. 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 Ca2Bi4Ti5O18. This work suggested that the Aurivillius ferroelectric Ca(2)Bi(4)Ti(5)O(18)is a promising candidate for photocatalytic applications.