Cost-Effective Production of Piezoelectric Single Crystals

The objective of this proposal is to demonstrate the feasibility of reducing the manufacturing costs for large-sized PMN-PT single crystals grown by a novel multi-crucible Bridgman method with a specially designed zone-leveling capability. This hybridmethod promises a cost-effective approach for the production of large-sized PMN-PT single crystals with improved compositional uniformity and quality control. The traditional Bridgman method is one of the simplest and most economic techniques for thegrowth of single crystals, but compositional variations in such multi-component PMN-PT systems leads to obvious property changes. Control of compositional homogeneity during the growth of PMN-PT crystals is a limiting factor for the successfulcommercialization of the next generation of PiezoCrystals and devices. Improvements in homogeneity and properties will lead to increased yields and reduced costs. The merit of the proposed technique is that: (a) multi-crucible configurations significantlyincrease the useful crystal yield/per run, (b) implementation of zone-leveling (with a large ratio of growth length (L) / molten-zone length (Z)) gives better control of compositional uniformity, and (c) self-refurbishment of platinum crucibles furtherreduces 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 thisnew 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 thefabrication of 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 besupplied to clients for the production of PiezoCrystal transduction devices for defense and civilian applications. The work will improve the properties of the next generation of piezoelectric crystals and reduce their manufacturing costs. The improvedelectromechanical materials will enable better commercial applications, including, transducers, sensors, actuators, and micro positioners, where higher signal-to-noise ratios and efficient energy conversion are required, e. g., acoustic imaging,accelerometers, hydrophones, and adaptive optics.