SBIR-STTR Award

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 hybrid method 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 the growth 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 successful commercialization 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 significantly increase 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 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 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.

Benefit:
The work will improve the properties of the next generation of piezoelectric crystals and reduce their manufacturing costs. The improved electromechanical 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.

Keywords:
Crystal Growth, Crystal Growth, PMN-PT single crystal, compositional homgeneity, Piezoelectrics, Bridgman, PMN-PT, Transducers, zone-leveling

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.

Benefit:
The proposed Phase II project is to provide an advanced development of a cost effective manufacturing method for mass production of large sized PMN-PT based piezoelectric crystals. The project will develop a series of production techniques of comprehensively self-contained and with industrial scale. The work will improve the properties of the next generation of PMN-PT based piezoelectric crystals and significantly reduce their manufacturing costs. The improved electromechanical materials will enable military and commercial applications, including, transducers, sensors, actuators, and micro positioners, where higher signal-to-noise ratios and efficient energy conversion are required, e. g., SONAR, countermeasure, acoustic guiding, ultrasonic imaging, accelerometers, hydrophones, and adaptive optics.

Keywords:
Domain Engineering, Zone leveling, Piezoelectric Crystal, Acoustic Transducers, Bridgman method, PMN-PT, Crystal Growth, Piezoelectrics