Fabrication of Textured 0.685TiO[sub.3]-0.065BaTiO[sub.3]-0.25SrTiO[sub.3] Electrostrictive Ceramics by Templated Grain Growth Using NaNbO[sub.3] Templates and Characterization of Their Electrical Properties

Electrostrictive materials based on (Na[sub.0.5]Bi[sub.0.5])TiO[sub.3] are promising lead-free candidates for high-precision actuation applications, yet their properties require further improvement. This study aims to enhance the electromechanical properties of a predominantly electrostrictive composition, 0.685(Na[sub.0.5]Bi[sub.0.5])TiO[sub.3]-0.065BaTiO[sub.3]-0.25SrTiO[sub.3], by using templated grain growth. Textured ceramics were prepared with 1~9 wt% NaNbO[sub.3] templates. A high Lotgering factor of 95% was achieved with 3 wt% templates and sintering at 1200 °C for 12 h. Polarization and strain hysteresis loops confirmed the ergodic nature of the system at room temperature, with unipolar strain significantly improving from 0.09% for untextured ceramics to 0.23% post-texturing. A maximum normalized strain, S[sub.max]/E[sub.max] (d[sub.33]*), of 581 pm/V was achieved at an electric field of 4 kV/mm for textured ceramics. Textured ceramics also showed enhanced performance over untextured ceramics at lower electric fields. The electrostrictive coefficient Q[sub.33] increased from 0.017 m[sup.4]C[sup.−2] for untextured ceramics to 0.043 m[sup.4]C[sup.−2] for textured ceramics, accompanied by reduced strain hysteresis, making the textured 0.685(Na[sub.0.5]Bi[sub.0.5])TiO[sub.3]-0.065BaTiO[sub.3]-0.25SrTiO[sub.3] composition suitable for high-precision actuation applications. Dielectric properties measured between −193 °C and 550 °C distinguished the depolarization, Curie–Weiss and Burns temperatures, and activation energies for polar nanoregion transitions and dc conduction. Dispersive dielectric constants were found to observe the “two” law exhibiting a temperature dependence double the value of the Curie–Weiss constant, with shifts of about 10 °C per frequency decade where the non-dispersive THz limit was identified.