IMF2017

Ferroelectric material based piezo-actuators had been widely used in modern industries due to their quick response, large actuation force, compact size, and the electric-driven style which is more convenient than magnetic driven or thermal driven ones. However, the widely used PZT-based actuators suffered from the rather small actuation strain, typically ~0.1%. Non-180⁰ domain switching can cause large strains up to ~1% in BaTiO₃ crystals and over 0.5% in PZT ceramics. However, these strains are usually irreversible and cannot be used in actuators. In this work, we firstly realized large actuation strains in ferroelectric single crystals via reversible domain switching under uniaxial electromechanical loading. The reversible strain can be up to 0.93% in BaTiO₃ and 0.66% in PMN-PT crystals. However, the crystals turn fractured after several hundred or thousand circles of operation. Recently, we realized large actuation strains up to 0.45% in a domain-engineered PZT ceramics at low field (2 kV/mm). Self-stressing occurs in this hybrid-domain PZT ceramics upon electric loading and the generated stresses caused back switching upon removing the electric field. The large reversible strain is stable after circles of operation, which is more promising for next generation large-strain actuators.