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Aurivillius phase Ca2Bi4Ti5O18 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. Ca2Bi4Ti5O18 ceramic exhibited frequency independent dielectric anomaly at 774°C. The piezoelectric coefficient d33 value of poled Ca2Bi4Ti5O18 pellets was 0.7 ± 0.2 pC/N. Both frequency independent dielectric anomaly and detectable d33 value clearly indicated that Ca2Bi4Ti5O18 is a ferroelectric material with Curie point of 774 ℃. UV–vis absorption spectra revealed that Ca2Bi4Ti5O18 had a direct band gap of 3.2 eV. Photocatalytic activity of the Ca2Bi4Ti5O18 powders was examined by degradation of rhodamine B (RhB) under simulated solar light. 16% of RhB solution was degraded by Ca2Bi4Ti5O18 powders after 4 hours UV‐vis irradiation. With Ag nanoparticles deposited on the Ca2Bi4Ti5O18 powders surface, 50% of RhB was degraded under the same irradiation condition. The fitted degradation rate constant of Ag decorated Ca2Bi4Ti5O18 was 4 times higher than that of bare Ca2Bi4Ti5O18. This work suggested that the Aurivillius ferroelectric Ca2Bi4Ti5O18 is a promising candidate for photocatalytic applications. [ABSTRACT FROM AUTHOR]

Lead‐free Aurivillius phase BaBi2Nb2O9 powders were prepared by solid‐state reaction. Ferroelectric measurements on BaBi2Nb2O9 (BBNO) ceramics at room temperature provided supporting evidence for the existence of polar nanoregions (PNRs) and their reversible response to an external electric field, indicating relaxor behavior. The photocatalytic degradation of Rhodamine B reached 12% after 3 hours irradiation of BBNO powders under simulated solar light. Silver (Ag) nanoparticles were photochemically deposited onto the surface of the BBNO powders and found to act as electron traps, facilitating the separation of photoexcited charge carriers; thus, the photocatalytic performance was significantly improved. The present study is the first examination of the photochemical reactivity of a relaxor ferroelectric within the Aurivillius family with PNRs. [ABSTRACT FROM AUTHOR]

Aurivillius phase Ca2Bi4Ti5O18 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. Ca2Bi4Ti5O18 ceramic exhibited frequency independent dielectric anomaly at 774°C. The piezoelectric coefficient d33 value of poled Ca2Bi4Ti5O18 pellets was 0.7 ± 0.2 pC/N. Both frequency independent dielectric anomaly and detectable d33 value clearly indicated that Ca2Bi4Ti5O18 is a ferroelectric material with Curie point of 774 ℃. UV–vis absorption spectra revealed that Ca2Bi4Ti5O18 had a direct band gap of 3.2 eV. Photocatalytic activity of the Ca2Bi4Ti5O18 powders was examined by degradation of rhodamine B (RhB) under simulated solar light. 16% of RhB solution was degraded by Ca2Bi4Ti5O18 powders after 4 hours UV‐vis irradiation. With Ag nanoparticles deposited on the Ca2Bi4Ti5O18 powders surface, 50% of RhB was degraded under the same irradiation condition. The fitted degradation rate constant of Ag decorated Ca2Bi4Ti5O18 was 4 times higher than that of bare Ca2Bi4Ti5O18. This work suggested that the Aurivillius ferroelectric Ca2Bi4Ti5O18 is a promising candidate for photocatalytic applications. [ABSTRACT FROM AUTHOR]

Lead‐free Aurivillius phase BaBi2Nb2O9 powders were prepared by solid‐state reaction. Ferroelectric measurements on BaBi2Nb2O9 (BBNO) ceramics at room temperature provided supporting evidence for the existence of polar nanoregions (PNRs) and their reversible response to an external electric field, indicating relaxor behavior. The photocatalytic degradation of Rhodamine B reached 12% after 3 hours irradiation of BBNO powders under simulated solar light. Silver (Ag) nanoparticles were photochemically deposited onto the surface of the BBNO powders and found to act as electron traps, facilitating the separation of photoexcited charge carriers; thus, the photocatalytic performance was significantly improved. The present study is the first examination of the photochemical reactivity of a relaxor ferroelectric within the Aurivillius family with PNRs. [ABSTRACT FROM AUTHOR]