Development of BaTiO3 / BiFeO3 composites for application in solar cells.

Reference	Presenter	Authors (Institution)	Abstract
08-117	Renato Boschilia Junior	Boschilia Junior, R.(Universidade federal de São Paulo); Antonelli, E.(Universidade Federal de São Paulo);	The most studied photoferroelectrics materials is BiFeO3 (BFO), which has a small optical bandgap (~2.7eV) and good chemical stability, also multiferroic behavior. However, the BFO has a high leakage current, which reduces its ferroelectric polarization and efficiency in solar cells. Nonetheless, BaTiO3 (BT) is known for its excellent ferroelectric properties, however it has a wide optical bandgap (~3.3eV), making it difficult to apply as photoferroelectrics material. The aim of this work was to produce and study BFO/BT composites for photoferroelectric application. For the synthesis of the composites, BFO and BT, were prepared by the conventional ceramic method until the calcination step. BT and BFO were mixed and milling in the proportions, (x)(BaTiO3)(1-x)(BiFeO3), x = 0.01, 0.10, 0.50, for composites preparation. The powders were pressing at 350 MPa to produce disk-shaped samples (10 mm diameter and 1 mm thick) using PVA as binder and then sintered at 900°C for 5h. The densities were determined using the Archimedes method. The crystallography phases and morphology of the ceramics were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The electrical properties were studied using impedance spectroscopy (IS) and optical properties using UV-VIS-NIR. The sintered ceramics of BT presented the single phase, otherwise in BFO were observed secondary phases that were identified as selenite phase. In the composites, were observed a decreasing in this secondary phase. The decrease in grains sizes were observed when BT concentration is increased. No phase transitions were observed in the permittivity curves. The electrical analysis reveals an increase in resistivity when BT concentration is increased. The optical characterizations are being processed and will be presented.
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