Improving the piezoelectric strain and anti-reduction properties of K0.5Na0.5NbO3-based ceramics sintered in a reducing atmosphere

摘要

Lead-free 0.945K(0.48)Na(0.52)Nb(0.96)Ta(0.04)O(3)-0.055BaZrO(3) + 6%MnO + xZrO(2) piezoelectric ceramics sintered in a reducing atmosphere were prepared by conventional solid-state reaction methods. The use of the ZrO2 dopant resulted in an increase in the rhombohedral (R) phase in orthorhombic (O)/R coexisting phases. Nonstoichiometric ZrO2 dopant addition could effectively improve the anti-reduction properties of KNN-based ceramics via controlling the oxygen vacancy concentration. In particular, 2% mol nonstoichometric ZrO2 dopant addition could improve the activation energy of the grain boundary (E-gb) via increasing the grain boundary thickness. The addition of the ZrO2 dopant could improve the fatigue resistance of the unipolar piezoelectric strain of 0.945K(0.48)Na(0.52)Nb(0.96)Ta(0.04)O(3)-0.055BaZrO(3 )+ 6%MnO ceramics. The optimum inverse piezoelectric coefficient d(33)* of ceramics at x = 0.01 reached up to similar to 465 pm V-1 at a low driving electric field E of 20 kV cm(-1) at room temperature, and the temperature stability of d(33)* reached 155 degrees C. After 10(6) unipolar fatigue cycles, the beta value of 0.945KNNT-0.055BZ + 6Mn + xZr ceramics could be preserved to more than 86%. The 0.945K(0.)(48)Na(0.)(52)Nb(0.)(96)Ta(0.)(04)O(3)-0.055BaZrO(3) + 6% MnO + xZrO(2) ceramic is a lead-free material with great potential to be applied in the fabrication of multilayer ceramic actuators with Ni inner electrodes in the future.