Strong piezoelectricity exhibited by large-grained BaTiO3 ceramics

A good understanding of the strong piezoelectric mechanism of BaTiO3 ceramics is very important from both scientific and technological viewpoints. This Letter reports an unusual piezoelectric phenomenon observed in a group of large-grained dense BaTiO3 ceramics with average grain sizes ranging from 5.1 to 16.3 mu m, which are prepared with a hydrothermally synthesized BaTiO3 fine powder by hot-press sintering. Among these BaTiO3 ceramics, the one possessing an average grain size of 5.6 mu m exhibits a particularly prominent piezoelectricity with piezoelectric constants d(33) = 485 pC/N and d(33)* = 725 pm/V at room temperature and a peak d(33) value of 574 pC/N around 8.5 degrees C. This ceramic is further investigated from the aspects of domain patterns and polarization versus electric field (P-E) loops and compared with a conventionally sintered BaTiO3 ceramic prepared using a solid-state reaction method. The investigation shows that it has the domain patterns of simple parallel stripes inside the grains and the square-like P-E loops and differs significantly from the conventionally sintered ceramic, and indicates that the observed strong piezoelectricity is strongly related to the large remanent polarization. (C) 2014 AIP Publishing LLC.