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Moreover, previous studies have investigated hard PZT compositions with low sintering temperatures, but they were not practically applied to cofired multilayer piezoelectric transformers. Therefore, research at Pennsylvania State University and Solid State Ceramics Incorporated (University Park, Pa.) investigated how to substantially lower process temperatures for a typical hard-PZT composition. This accomplishment would allow use of less expensive electrode materials, such as silver or silver–palladium, and base-metal electrodes, such as copper. To realize these goals, the team developed modified hard- PZT piezoceramic compositions with low sintering temperatures (≤1,000˚C). It demonstrated high efficiency of these materials in multilayer piezoelectric transformers with silver– palladium cofired electrodes with low palladium content (i.e., 90/10 and 95/5). The team also investigated the feasibility of copper cofiring and prototyped copper cofired multilayer piezoelectric transformers. The efforts included typical multilayer prototyping for overall and ambient sintering for silver–palladium cofired piezoelectric transformers. Scientists used reducing-atmosphere sintering for copper cofiring feasibility investigations and copper cofired piezoelectric transformer prototypes. The results show that by using less-expensive electrode materials—specifically base-metal electrodes, such as copper—it is possible to significantly reduce the cost of piezoelectric transformers so that they can compete with the cheaper price of electromagnetic transformers. Moreover, initial characterizations on copper cofired multilayer transformers show significantly improved thermal and electrical behaviors compared to other materials, which should correlate with significant improvements in device performance. With recent improvements in piezo-driver technology, in conjunction with these developments, the tremendous potential of piezoelectric transformers can be realized in the electronics industry. n Starbar and Moly-D elements are made in the U.S.A. with a focus on providing the highest quality heating elements and service to the global market. I R -- 50 years of service and reliability 2 I Squared R Element Co., Inc. Akron, NY Phone: (716)542-5511 Fax: (716)542-2100 Email: sales@isquaredrelement.com www.isquaredrelement.com Multilayer piezoelectric transformers cofired with (left to right) platinum, silver–palladium (95/5), and copper electrodes. Mechanical Hydraulic Isostatic High Speed Sintering Vacuum Visit Gasbarre Products, Inc. at Ceramics Expo Cleveland, Ohio 590 Division Street | DuBois, Pennsylvania 15801 | +1-814-371-3015 press-sales@gasbarre.com | www.gasbarre.com Industrial Heat Treat Gasbarre | Simac | PTX | Sinterite | C.I. Hayes | J.L. Becker | McKee Carbide Tool | Major Gauge & Tool Credit: Solid State Ceramics Inc.; Pennsylvania State University American Ceramic Society Bulletin, Vol. 95, No. 3 | www.ceramics.org 19


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