Voltage gain characteristics of piezoelectric transformer using PbTiO 3 system ceramics

Abstract

PbTiO 3 system ceramics were suitable to be used for a piezoelectric transformer, operating in thickness extensional vibration mode because these are materials with large anisotropy of electromechanical coupling factor, k t/ k p. In this paper, the (Pb 0.76Ca 0.24)[(Co 0.5W 0.5) 0.04Ti 0.96]O 3+1.5 mol% MnO 2 ceramic system for piezoelectric transformers were manufactured. Its electromechanical coupling coefficients, k t of 49% and k p of near zero, which give rise to large anisotropic property, k t/ k p, were obtained from the specimen sintered at 1150°C. A piezoelectric transformer that is 20 mm long, 20 mm wide and 3.1 mm thick was fabricated using this composition ceramic. Resonant frequencies of second thickness extensional vibration mode are 1.56 and 1.58 MHz at loading resistance 100 and 200 Ω, respectively. Maximum voltage gain of piezoelectric ceramics was 0.72 and 0.86 at resonant frequency of second thickness extensional vibration mode at loading resistance 100 and 200 [Ω], respectively.