| Abstract
| - A hybrid film of layered niobate and an organic amphiphile was prepared by the Langmuir−Blodgett (LB)method. Trimethylammonium-exchanged perovskite-type niobates ((CH3)3NHSr2Nb3O10) were exfoliative toform an aqueous suspension. A monolayer of octadecylamine was produced on such an aqueous dispersionas a template for a hybrid film. A hybrid film was transferred as a Y-type LB film onto a hydrophilic glassplate or an ITO substrate. The structure of a deposited film was investigated with X-ray diffraction (XRD),Fourier transform infrared (FT-IR), and atomic force microscopy (AFM) measurements, indicating a layer-by-layer structure with a single or double sheet of niobate as an inorganic composite. From the cyclicvoltammogram on an ITO electrode modified with the Y-type 10 layered film, the lower edge of the conductionband of a niobate layer was determined to be − 0.6 V (vs Ag/AgCl). ac impedance and dc measurementswere carried out on 1, 5, and 10-layered LB films (2 mm (electrode spacing) × 8 mm (width)) with aluminumelectrodes. The freshly deposited samples behaved as an insulator under the illumination of 280 nm light(2.04 × 1016 quanta s-1). Photoconductivities appeared, however, when they were preirradiated with a 150W Xe lamp (ca. 2 × 1018 quanta s-1) for 0.5−8.5 h. The process was denoted as photomodification. Fromthe FT-IR and XRD results, it was deduced that the photomodification of LB films caused the decompositionof organic templates (octadecylammonium) accompanied by the collapse of layer-by-layer structures. dcanalyses on the 5- and 10-layered films after photomodification also showed that they behaved as aphotosemiconductor under UV light illumination.
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