Piezoelectric and Dielectric Properties of (Na_(0.5)K_(0.5))NbO_3-(Bi_(0.5)Na_(0.5))_(0.94)Ba_(0.06)TiO_3 Lead-Free Piezoelectric Ceramics

摘要

Lead-free piezoelectric ceramics (1 - x)(Na_(0.5)K_(0.5))NbO_3-x(Bi_(0.5)Na_(0.5))_(0.94)Ba_(0.06)TiO3 (abbreviated as NKN-BNBT100x, x - 0-0.10) were fabricated by a conventional mixed oxide route, and the effects of BNBT on electrical properties and crystal structures were investigated. X-ray diffraction analysis results indicate that BNBT diffuses into the NKN lattice to form a solid solution during sintering. All samples show pure perovskite structures and an orthorhombic-tetragonal phase transition with increasing x. The tetragonality, however, declined with further increasing x. The dielectric and piezoelectric properties are enhanced for the composition near the orthorhombic-tetragonal morphotropic phase boundary. The NKN-BNBT4 ceramics show good performance with piezoelectric constant d_(33))= 256 pC/N, planar electromechanical coupling factor k_p = 43%, and dielectric constant ε_(33)~T/ε_0 = 875. The results reveal that (1 - x)(Na_(0.5)K_(0.5))NbO_3-x(Bi_(0.5)Na_(0.5))_(0.94)Ba_(0.06)TiO_3 ceramics are promising candidate materials for lead-free piezoelectric application.