Piezoelectric and Dielectric Properties of (Bi_(0.5)Na_(0.5))_(0.94)(Ba_(1-x)Sr_x)_(0.06)TiO_3 Lead-free Piezoelectric Ceramics

摘要

Lead-free piezoelectric ceramics (Bi_(0.5)Na_(0.5))_(0.94)(Ba_(1-x)Sr_x)_(0.06)TiO_3 (abbreviated as BNBST-100x, with x ranges from 0.02 to 0.1) have been investigated. Effects of amount of Sr-substitution on the electrical properties and crystal structure of the ceramics were studied. The BNBST-100x ceramics sintered at 1200°C for 2h in air have high density around 5.69～5.75g/cm~3. X-ray diffraction (XRD) analysis shows that all of the BNBST-100x ceramics have pure perovskite structure. At high amount level of Sr-substitution, the crystal structure of the samples changes from rhombohedral to tetragonal symmetry. Piezoelectric and dielectric measurements reveal that Sr-substitution amount within a certain range will lead to the increase of piezoelectric coefficient (d_(33)), electromechanical coupling factor (k_P), and relative dielectric constant (ε_(33)~T/ε_0). At 6 mol% Sr-substitution level, the d_(33) and k_P of the ceramics reach maximum, with values of 168 pC/N and 34%, respectively.