Remarkably Strong Piezoelectricity of Lead-Free Ceramic

摘要

Various lead-free (K^Naj^ ceramics with a: = 0.50, y = 0.00-0.07 or x = 0.40-0.60, y = 0.05 were prepared by the conventional solid-state reaction method. Systematic investigation on the microstructures, crystalline structures, and dielectric and piezoelectric properties was carried out. Remarkably strong piezoelectricity has been achieved in (Ko.4sNao.55)o.98L?o.o2(Nbo.77Tao.i8Sb005)03 ceramic, which shows the excellent piezoelectric properties of d33 = 413 pC/N, d31 = -153 pC/N, k9 = 0.50, and k33 = 0.62. It is considered that the observed strong piezoelectricity should be ascribed to several combined decisive factors, such as the phase coexistence due to an orthorhombic-tetragonal polymorphic phase transition near room temperature, the high electron-egativity of Sb5+ ions as compared with those of Nb ions and Ta5+ ions, and the relatively ideal microstructure with high density, large average grain size and narrow grain-size distribution.