Progress in studies on fabrication and properties of PZNT relaxor ferroelectrics

The present paper reviews the recent progress in studies on fabrication and dielectric piezoelectric and electrostrictive properties of relaxer ferroelectric PZNT. The dominant method of fabrication of PZNT is the PbO flux method at high temperature, by which the single crystals with size of 40mm have been grown. Studies on their dielectric properties indicated that the behavior of phase transition of PZNT crystals would vary from diffused, mixed to first order transition type with the increase of PT concentration. The rhombohedral-tetragonal ferroelectric phase transition is also diffused which can be induced by composition or electric field. Single crystals with their composition at MPB or in the rhombohedral phase region near MPB have extremely strong piezoelectric properties. The < 001 > oriented rhombohedral and tetragonal crystals are respectively suitable for acoustic arrays and single element sensors and actuators with broader bandwidth, improved sensitivity and optimum impedance matching. Crystallographically, high strains are achieved for < 001 > oriented rhombohedral crystals and their levels reach an order of magnitude of those available from conventional piezoelectric and electrostrictive ceramics such as PZT series and PMNT ceramics, which make these crystals as promising candidates for high performance solid actuators.