Large Strain Response in the Ternary Bi0.5Na0.5TiO3-BaTiO3-SrTiO3 Solid Solutions

A ternary solid solution (0.935-x)Bi0.5Na0.5TiO3–0.065BaTiO3–xSrTiO3 was designed and fabricated using a conventional fabrication process. Temperature and composition dependence of the ferroelectric, dielectric, and piezoelectric properties were systematically investigated and a schematic phase diagram was established. The SrTiO3 substitution was found to induce a transition from ferroelectric to relaxor pseudocubic phases. Around a critical composition x of 0.22, large strain response of ~0.2% (under a moderate field of 4 kV/mm) with normalized strain of 490 pm/V was obtained. The large unipolar strain response would be of great interest for environmental-friendly “on-off” actuators.