Top-cooling-solution-growth and characterization of piezoelectric 0.955Pb(Zn1/3Nb2/3)O3-0.045PbTiO3 [PZNT] single crystals

A technique of top-cooling-solution-growth (TCSG) has been developed to grow the piezo-/ferroelectric perovskite single crystals of 0.955Pb(Zn1/3Nb2/3)O-3-0.045PbTiO(3) [PZNT95.5/4.5]. The flux composition and concentration, and the thermal parameters have been optimized, leading to the growth of high quality PZNT crystals with a size up to 20 x 15 x 10 mm(3). The perovskite crystals are found to form upon slow cooling down to 1020 degreesC, while the undesirable pyrochlore crystals of Pb1.5Nb2O6.5-type start growing upon further cooling from 1020 degreesC to 950 degreesC. By controlling the growth pathway, the formation of the pyrochlore phase can be avoided. The dielectric properties of the grown PZNT95.5/4.5 crystals have been measured as a function of temperature at various frequencies. Upon heating, the phase transition for the rhombohedral R3m to the tetragonal P4mm phase takes place at 132 degreesC, while the tetragonal to cubic phase transition occurs at 160 degreesC. The TCSG developed in this work provides an alternative technique to grow PZNT piezocrystals of medium size at low cost for transducer applications. (C) 2001 Kluwer Academic Publishers.