PHOTOEFFECTS IN LA-3+-DOPED BATIO3 CERAMIC ELECTRODES

Photoelectrochemical conversion characteristics of semiconducting, polycrystalline BaTiO3 electrodes have been investigated as a function of sintering atmosphere (air/H2) and the amount of dopant (lanthanum). The photocurrents for specimens sintered in air were greater than those of specimens sintered in hydrogen. Also, as the amount of dopant in BaTiO3 sintered in air increased, the photocurrent increased up to 0.2 at. % addition and then decreased. However, for BaTiO3 sintered in hydrogen, the photocurrents decreased consistently with the addition of the dopant. These results could be explained in terms of ceramic microstructure and electrical resistivity. Regardless of the amount of lanthanum, the photoresponse, as the wavelength of the induced light that varied, began to appear around 420-430 and 780-800 nm, which corresponds to the energy band of La-doped BaTiO3 and the oxygen vacancy level within the gap, respectively.