Temperature‐ and Frequency‐Dependent Properties of the 0.75Bi1/2Na1/2TiO3–0.25SrTiO3 Lead‐Free Incipient Piezoceramic

The dielectric and electromechanical properties of 0.75 Bi 1/2 Na 1/2 TiO 3 –0.25 SrTiO 3 (25 ST ) as a function of temperature and frequency were studied. It is shown that the 25 ST is a relaxor ferroelectric as evidenced by the temperature‐dependent dielectric relaxations with an incipient piezoelectricity featured by the presence of a reversible electric‐field‐induced phase transformation at room temperature. The transition occurs on a broad electric field strength range depending on field amplitude and frequency. It is also accompanied by a huge strain that is attributed to repetitive poling and depoling originating due to the reversibility of the phase transition. The 25 ST makes an attractive lead‐free candidate for stack actuators as it presents a high normalized d 33 * of ~600 pm/V at a low electric field of 4 kV/mm for frequencies ranging from 0.1 up to 100 Hz.