THE ROLE OF PROCESSING VARIABLES IN THE FLUX GROWTH OF LEAD-ZINC NIOBATE-LEAD TITANATE RELAXOR FERROELECTRIC SINGLE-CRYSTALS

Relaxer ferroelectric single crystals of Pb(Zn1/3Nb2/3)O-3-PbTiO3 (PZN -PT) are of interest as high performance transducers due to their very large piezoelectric coupling and dielectric properties. A high temper ature flux solution method was used to grow (1-x)PZN-(x)PT, where x = 0.0, 0.1 and 0.15 single crystals. Processing conditions were optimize d to increase the size and yield of the perovskite crystals, including variation of the flux to composition ratio, cooling rate, soak time a nd soak temperature. The crystals varied in size from 0.01 cm to 1.5 c m on an edge, and in color from opaque to brown due to the changes in processing conditions. The crystals were characterized by XRD, dielect ric constant and dielectric loss measurements. As the content of PT in creased the transition from the paraelectric to the ferroelectric phas e approached first order behavior and the crystal structure transforme d from rhombohedral to tetragonal. This structure transition caused th e lattice constant along the c-axis to elongate as the cia ratio incre ased. At room temperature, the dielectric constants for the PZN-PT com positions along the [111] or [001] axes were as great as 5000 and the dielectric losses were as low as 0.01.