Cost-Effective Production of Piezoelectric Single Crystals

: The development of cost-effective manufacturing technique for PMN-PT based piezoelectric single crystals with enhanced capabilities is critical to the achievement of the new generation of acoustic transduction devices. In Phase I, feasibility of the novel technique was demonstrated. The objective of this research project is to continue development of reducing the manufacturing costs for large-sized PMN-PT single crystals grown by a novel hybrid method, the combination of multi-crucible (8~10) Bridgman method and zone-leveling technique with a specially designed batch reservoir on crucibles. This hybrid method promises a cost-effective approach for mass production of large-sized PMN-PT single crystals with improved compositional uniformity and quality control. The distinctive features of the phase II project are that: (1) the number of crucibles/per furnace will be increased up to 10; (2) the diameter of each crucible will be enlarged up to 3 inches; (3) implementation of zone-leveling gives better control of compositional uniformity; (4) self-fabricated platinum crucible with a specially designed reservoir to enhance zone leveling effect with lower probability of crucible leaking, and (5) self-refurbishment of platinum crucibles further reduces the costs of manufacture. The proposed work is directed at evaluating PMN-PT crystal quality by relating piezoelectric properties with compositional analysis of the boules. Audit of the manufacturing costs for PMN-PT single crystals grown by this new method will be made by a detailed consideration of the costs for platinum, materials, man power, environmental control, equipment depreciation and capitalization. The proposed crystal growth method will be of immediate applicability to the fabrication of 2~3 inch-sized devices with uniform piezoelectric properties. Anticipated work in Phase II would be extended to larger sizes. The PMN-PT single crystal products, such as, poled or un-poled plates, disks, rings, cylinders and wedges, will be supplied to clients for the production of PiezoCrystal transduction devices for defense and civilian applications.