Growth and characterization of lead-free ferroelectric (K,Na,Li)(Nb,Ta,Sb)O3 single crystal

• High quality large size Li, Sb, Ta co-doped (K,Na)NbO3 single crystal was successfully grown.
• The tetragonal crystal shows homogenous composition.
• The [001]C oriented single crystal shows relatively good piezoelectric properties.
• The electromechanical coupling factor kt of the crystal exhibited very good thermal stability.

In this work, a large size lead-free piezoelectric single crystal, (K,Na,Li)(Nb,Ta,Sb)O3 (KNLNTS) with the dimensions of 8.5×8.5×13.5 mm3 was successfully grown by the top-seeded solution growth method. This KNLNTS single crystal with high compositional homogeneity is in the tetragonal phase at room temperature. The Curie temperature TC of the tetragonal-cubic phase transition temperature is 210 °C. The piezoelectric coefficients and electromechanical coupling factors of the [001]C oriented KNLNTS single crystal are d33=172.55 pC/N, d31=−71.90 pC/N, k31=0.327, k33=0.523, and kt=0.541. In addition, the crystal shows good thermal stability so that it can be used for making high temperature electromechanical devices.