Our twenty first century will face a sustainable society, which requires (a) usage of nontoxic materials, (b) disposal technology for existing hazardous materials, (c) new energy source creation, and (d) energy-efficient device development. Piezoelectric devices seem to be all-around contributors and a key component to the above-mentioned four R&D areas in the sustainable society. Since the most widely used piezoelectric lead zirconate titante (PZT) ceramics will be regulated in less than 10 years in European and Japanese communities due to their toxicity (Pb2+ ion), lead-free piezoelectric ceramics have been developed with performance equivalent to the PZTs. This paper introduces the current status of promising applications of Pb-free piezoelectrics developed recently: (1) piezoelectric transducers for ultrasonic cleaners, (2) piezoelectric transformers, and (3) ultrasonic motors with multilayer piezoactuators.
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