Top-Seeded Solution Growth and Properties of K_1–<i>x</i>Na_<i>x</i>NbO₃ Crystals

Abstract

A series of large-sized (maximum 16 × 16 × 20 mm3), high-quality K1–xNaxNbO3 (x = 0.118, 0.378, 0.462, 0.545, and 0.666) single crystals were successfully cultivated using the top-seeded solution growth method. The crystallization and structures of the K1–xNaxNbO3 single crystals were studied using first-principles calculations and X-ray diffraction, respectively. The segregation of the K1–xNaxNbO3 single crystals was investigated, which enabled precise control of the individual components of the crystals during growth. Excellent properties were obtained without annealing, including a low dielectric loss (minimum 0.2%), a saturated hysteresis loop with a low coercive field Ec, a large piezoelectric coefficient d33 (d33 = 161 pC/N when x = 0.378), and a low leakage current density J (10–6 A/cm2). These results indicated that the K1–xNaxNbO3 (x = 0.118, 0.378, 0.462, 0.545, and 0.666) crystals can be used as a high-quality, lead-free piezoelectric material.