Improved Growth of Large Lead Zinc Niobate Titanate Piezoelectric Single Crystals for Medical Ultrasonic Transducers

Abstract

Large piezoelectric single crystals of the Pb[(Zn 1/3 Nb 2/3 ) 0.91 Ti 0.09 ]O 3 (PZN-PT) binary system have been successfully obtained using a conventional flux method and a suitable ratio of PZN-PT: PbO flux. The largest crystal had dimensions of 43×42×40 mm and weighed 415 g. In order to improve growth behavior and reduce the number of nuclei, the temperature gradient program of the crucible was optimized; that is, the bottom of the crucible was made cooler (>50° C) than the top during cooling. A charged composition of 45 mol% PZN-PT and 55 mol% PbO showed good growth results. A large bar-mode electromechanical coupling factor, k 33 ', (84%) for phased array ultrasonic transducers was obtained. This confirms that large PZN-PT single crystals for phased-array ultrasonic transducers can be grown using a flux method.