Effect of dielectric relaxation on the performance of P(VDF-TrFE) copolymer ultrasonic transducers

The complex dielectric permittivity of vinylidene fluoride-trifluoroethylene copolymer with 20 mol% of TrFE [P(VDF-TrFE) 80/20] has been measured over the frequency range of 500 kHz to 20 MHz at temperatures varying from 20/spl deg/ to 100/spl deg/C. This copolymer has the highest electromechanical coupling coefficient k/sub t/ among all TrFE compositions and has thus attracted considerable interest in ultrasonic transducer applications. The effect of dielectric relaxation on the performance of VDF-TrFE transducers is discussed.