Voltage gain characteristics of piezoelectric transformer using PbTiO3 system ceramics

PbTiO3 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(l)/k(p). In this paper, the (Pb0.76Ca0.24)[(Co0.5W0.5)(0.04)Ti-0.96]O-3 +1.5 mol% MnO2 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 degrees C. A piezoelectric transformer that is 20 mm long, 20 mm wide and 3.1 nun 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 Omega, 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 [Omega], respectively. (C) 1999 Elsevier Science S.A. All rights reserved.