Dielectric and Piezoelectric Properties of High Curie Temperature Single Crystals in the Pb(Yb_1/2Nb_1/2)O₃–xPbTiO₃ Solid Solution Series

Piezoelectric single crystals in the (1-x)Pb(Yb_1/2Nb_1/2)O₃–xPbTiO₃ (PYN–xPT) solid solution series were grown by a conventional high temperature solution method using PbO flux. The Curie temperature for compositions grown near the morphotropic phase boundary (x=0.5) was in the range from 300 to 400°C due to compositional variations and the addition of 1 mol% Ba²⁺, added for perovskite stability. With increasing PT content, the dielectric properties continuously changed from relaxor to normal ferroelectric behavior in the range of 0.2< x <0.8. The coercive field (E_c) for rhombohedral crystals near the MPB was 10–15 kV/cm, increasing to 20 kV/cm for the tetragonal crystals. The remnant polarization (P_r) also increased with the increasing of PT content from 0.9 µC/cm² (x=0.2) to 42 µC/cm² (x=0.53). The piezoelectric coefficient (d₃₃) of PYN–xPT single crystals increased with increasing PT content in the rhombohedral phase, being ∼2500 pC/N near the MPB composition (x=0.46), and decreasing to ∼1200 pC/N for the tetragonal phase crystals. These excellent piezoelectric properties together with the high Curie temperature make PYN–xPT single crystals promising candidates for the applications of high temperature and high performance actuators and transducers.