Bismuth Layer-Structured Ferroelectric Ceramics with High Mechanical Quality Factor

The piezoelectric properties in some bismuth layer-structured ferroelectric (BLSF) ceramics were investigated focusing on a mechanical quality factor, Q(m). Many BLSF compositions with various Curie temperatures, T-c, were selected in this study, and the Q(m) values of (33) mode were plotted as a function of their Curie temperature, T-c. The Q(m) increased with increasing the T-c in the low-T-c compositions below 500 degrees C. It is considered to relate with the domain with pinning because the coercive field E-c also increased with increasing the T-c. However, in the high-T-c compositions above 750 degrees C, the Q(m) decreased with increasing the T-c, because of the difficulties in poling treatment due to the E-c. On the other hand, high Q(m) values exceeding 10,000 were obtained in the intermediate-T-c compositions between 500 and 750 degrees C. These values are quite high as the piezoelectric ceramics. The key point of the high Q(m) in these compositions is the poling process at high temperature of 300 degrees C. (C) 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 91(12): 39-45, 2008; Published online in Wiley InterScience DOI 10.1002/ecj.10185