Good temperature stability and high piezoelectric properties of pure and La-doped tetragonal (K_(0.45)Na_(0.55))_(0.94)Li_(0.06)-Ta_xNb_(1-x)O_3 ceramics

摘要

Pure and La-doped tetragonal (K_(0.45)Na_(0.55))_(0.94)Li_(0.06)-Ta_xNb_(1-x)O_3 lead-free ceramics were prepared by the conventional sintering method. The piezoelectric properties and the temperature dependence of these ceramics were investigated. Both good temperature stability and high piezoelectric properties were obtained in tetragonal-phase (K_(0.45)Na_(0.55))_(0.94)Li_(0.06)-Ta_xNb_(1-x)O_3 ceramics. La was employed to reduce the effect of PPT and further improve the temperature stability of (K_(0.45)Na_(0.55))_(0.94)Li_(0.06)-Ta_(0.35)Nb_(0.65)O_3 ceramics. 0.5mol% La-doped (K_(0.45)Na_(0.55))_(0.94)Li_(0.06)-Ta_(0.35)Nb_(0.65)O_3 ceramics show the optimum properties (high piezoelectric properties: d_(33) = 152 pC/N and k_p = 30.5% and good temperature dependence: |Δf_r/f_r 20°c|_(max) = 0.79% and |Δk_p/k_p 20°c|_(max) =2.11% in the temperature region 20-80 °C).