Voltage gain characteristics of piezoelectric transformer using PbTiO3 system ceramics

PbTiO3 system ceramics were suitable to be used for a piezoelectric transfo rmer, operating in thickness extensional vibration mode because these are m aterials 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 mo l% MnO2 ceramic system for piezoelectric transformers were manufactured. It s electromechanical coupling coefficients, k(t) of 49% and k(p) of near zer o, which give rise to large anisotropic property, k(t)/k(p), were obtained from the specimen sintered at 1150 degrees C. A piezoelectric transformer t hat is 20 mm long, 20 mm wide and 3.1 nun thick was fabricated using this c omposition ceramic. Resonant frequencies of second thickness extensional vi bration 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 a t loading resistance 100 and 200 [Omega], respectively. (C) 1999 Elsevier S cience S.A. All rights reserved.