Local DC electrical properties of La_2/3&minus;<i>_x</i>Li₃<i>_x</i>TiO₃ grain boundaries

Abstract

Local DC electrical measurements were carried out to clarify the electrical properties of the grain boundaries of La 2/3¹x Li 3x TiO 3 ceramics. The I-Time curves exhibited a steep current decay with respect to time. The curves showed that the grain boundaries exhibited two types of behaviours. Partial grain boundaries were found to exhibit a higher current flow than the other curves. An equivalent circuit analysis was conducted with a circuit consisting of both resistance and capacitance components. The analysis results indicated that the partial grain boundary exhibited a larger capacitance, which was regarded as being the origin of the higher current flow. The increased capacitance was explained by the piling up of ions near the grain boundary, as a result of the boundary layer capacitance effect. These findings indicate that the conductivity of La 2/3¹x Li 3x TiO 3 ceramics could possibly be improved by controlling the electrical properties of the grain boundaries themselves, rather than by simply reducing the density.