Crystal Structure and Properties of Na2O-Modified K_(0.47)Na_(0.47)Li_(0.06)Nb_(0.96)Sb_(0.04)O3-SrTiO3 Piezoelectric Ceramics

摘要

Na2O-modified (1-x)K_(0.47)Na_(0.47)Li_(0.06)Nb_(0.96)Sb_(0.04)O3-SrTiO3 (abbreviated as KNLNS-ST, x = 0, 0.015, 0.035, 0.055, 0.08) Lead-free piezoelectric ceramics were fabricated by conventional ceramics sintering technique at 1050 °C and their crystal structure, dielectric and piezoelectric properties were systematically investigated. The X-ray diffraction revealed that all ceramics possessed a pure perovskite structure and a morphotropic phase boundary between the tetragonal and rhombohedral phases was identified in the composition range of 0.015 ≤ x ≤ 0.035, leading to a significant improvement in the electrical properties of the ceramics. The ceramic with x = 0.035 exhibited excellent properties at room temperature (d_(33)=186pC/N, k_p= 42 %, ε_r= 1116, tan δ= 1.8 %) owning to the formation of morphotropic phase boundary. These results indicated that the ceramic is a promising candidate material for lead-free piezoelectric ceramics.