Seeded Growth of Relaxor Ferroelectric Single Crystals Pb[(Zn_1/3Nb_2/3)_0.91Ti_0.09]O₃by the Vertical Bridgman Method

Abstract

Relaxor ferroelectric single crystals Pb[(Zn1/3Nb2/3)0.91Ti0.09]O3 (PZNT91/9) with a dimension of 30 mm in diameter and 25 mm in length have been grown by the modified vertical Bridgman method using PbO as the flux. Initially, seed crystals were obtained by cooling high-temperature solutions at the rate of 0.8–2°C/h. PZNT91/9 crystals were grown in a platinum crucible with a seed well of φ10 mm×60 mm from different solutions. It is difficult to grow perovskite PZNT crystals from 91 mol% Pb(Zn1/3Nb2/3)O3–9 mol% PbTiO3 melts with a surplus of PbO due to the competition of the pyrochlore phase. Additionally, a Pt crucible is prone to severe erosion by PbO at high growth temperatures. The optimum flux concentrations were found to be 45–55 mol% and the growth rate was 0.3–0.6 mm/h. Twelve pieces of PZNT wafers without any PbO striation were obtained. The dielectric properties of the grown crystals were determined.