The piezoelectric effect in Na_0.5Bi_0.5TiO₃ ceramics

Piezoelectric properties of Na_0.5Bi_0.5TiO₃ ceramics have been investigated over a broad temperature range using a resonance technique. The thermal behaviours of the piezoelectric tensor coefficients d₃₁, d₃₃ and d₁₅ confirm that there is a distinct phase transformation at 200 °C. For the first time it has been found that a piezoelectric signal connected with the tensor component d₃₃ is observed up to 280 °C. This corresponds to earlier neutron and x-ray diffraction data on the point of transition from rhombohedral to tetragonal symmetry.