Experimental studies of electrical conduction mechanism of H2-reduced BaTiO3

ESR, resistivity and Seeback coefficient measurements have been performed on both ceramics and single crystals of reduced semiconducting BaTiO₃.From the results that the observed temperature dependence of the Seeback coefficient can be explained by the temperature dependence of carrier concentration estimated from the electric resistivity making use of the data of electron mobility, it is concluded that the electric conduction in reduced BaTiO₃ is due to the band conduction rather than to the hopping process. From the measurement of the temperature dependence of the ESR intensity of the F-center, the number of electrons trapped at the F-centers decreases exponentially with temperature, while the number of conduction electrons increases. This temperature dependence can not be simply explained as that of the unionized donors in semiconductor. Therefore, the ESR signal considered as that of the F-center may not be due to simple donors, even though some of the conduction electrons may be originated in them.