A generalized rule for large piezoelectric response in perovskite oxide ceramics and its application for design of lead-free compositions

We present a general rule for the perovskite oxide ceramics: "A large piezoelectric constant in A B O 3 perovskite ceramics can be obtained by tuning the weight ratio of A and B sites, W A / W B or W B / W A , to 3. Piezoelectric constant decreases significantly when W A / W B or W B / W A is in the range of 0.5-2.0, termed as forbidden zone." A comparative analysis was conducted for broad range of materials demonstrating the applicability of proposed rule. Further based on this rule optimized compositions in BaTiO 3 and alkali niobate based systems were developed. Polycrystalline ceramics in modified BaTiO 3 system were found to exhibit longitudinal piezoelectric coefficient ( d 33 ) of 330 pC/N, while alkali niobate ceramics showed d 33 of 294 pC/N.