Cost-Effective Production of Piezoelectric Single Crystals

An experimental program has been proposed to economically fabricate PMN-PT single crysal discs, 25mm in diameter and 10 mm in thickness, via the solid-state conversion method. Cerone has demonstrated the fabrication of PMN-PT single crystals as large as 5mm x 5 mm x 2.5 mm and proposes to further optimize its proprietary solid-state conversin method in the proposed Phase I prgram.The proposed processes are described briefly as follows. First, fully dense ceramic dscs made of high purity PMN-PT powder are produced by a combination of pressureless sintering and hot-isostatic pressing. Second, the ceramic discs are ground to auniform thickness and one of their surfaces is polished to a 1/4 micron diamond finish. PMN-PT single crystal seeds are prepared likewise. Third, the polished surfaces of the ceramic disc and seed are paired and heated at an elevated temperature to fusethem together. Finaly the pairs are heated at an elevated temperature under a gaseous pressure to completely convert the ceramic discs into single crystals.The latest cost analysis indicates that the solid-state conversion method is a cost-effective way to produce PMN-PT single crystal discs at a price competitive to that of high-quality ceramics. The proposed program will demonstrate a cost-effective way to fabricate PMN-PT single crystal discs. Because of excellent uniformity of their chemical compositions and thus, their very uniform electromechanical and dielectric properties, variouselectromechanical components for sensors and actuators can be mass-produced economically using readily available semiconductor processing equipment.