Effects of Grain Boundaries on Photovoltaic Current and Photoinduced Domain Switching in Ferroelectric Ceramics

We investigated the effect of the grain size on the photovoltaic current in (Pb 1-x La x )TiO₃ ceramics, and the photoinduced domain switching in (Pb 0.85 La 0.15 )TiO₃ and BaTiO₃ ceramics. These behaviors in ferroelectric ceramics were attributed to the grain boundary at which photoexcited electrons were trapped. As the charged grain boundary acted as an electro-potential barrier which impeded the movement of electrons, the photovoltaic current showed a peak at a critical grain size. The space charge field built by the electrons trapped at the grain boundaries was accounted for the photoinduced domain switching, and AE experimental results support well this account.