W. Liu, National Institute for Materials Science, Tsukuba, Japan
Acceptor doping and donor doping have been known to result in opposite aging effect. Here, we report aging effect in hybrid-doped (donor+acceptor) BaTiO3 ceramics with donor (Nb5+)/acceptor (Mn3+) ratio between 0.5 and 2. We found surprisingly that no matter whether acceptor was in excess or donor is in excess, the hysteresis loops of all the hybrid-doped samples showed double ones after aging. Meanwhile the coercive field and hysteresis became smaller with increasing donor (Nb5+) concentration. These features created an important consequence on the electrostrain effect due to domain switching: a large non-linear recoverable electrostrain up to 0.17% was observed at 3kV/mm in un-poled samples after aging with small hysteresis and coercive field. This strain exceeds that of the mono-doped (Mn3+-doped) (BaSr)TiO3 ceramics, and the piezoelectric strain of hard PZT. These results demonstrate that hybrid doping is an effective way to enhance the domain-switching-related electrostrain properties. Finally, the aging effect of hybrid-doped ferroelectrics was explained.
Summary: Strong electri-field induced shape memory effect was achieved based on a new mechanism in the aged but unpoled hybrid doped BaTiO3 ceramics, an environmentally friendly lead-free material.
