非化学计量比对(K0.465Na0.465Li0.07)(Nb0.95Sb0.05)O3无铅压电陶瓷结构及性能的影响

通过传统固相合成工艺制备了(K0.465+xNa0.465+yLi0.07)(Nb0.95-zSb0.05)O3(x,y,z=-0.01～0.02)无铅压电陶瓷,研究了非化学计量比对陶瓷结构及压电性能的影响。结果表明符合化学计量比的陶瓷具有四方钙钛矿结构;在实验范围内,K和Nb的过量或少量均不会改变体系的相结构,而Na过量将会导致体系正交-四方相变温度升高到室温以上,并且正交-四方相变温度随y的增加而升高;过量添加约0.5%(摩尔分数)的K或Na便能补偿在高温烧结时的碱金属元素的挥发损失,进而提高陶瓷的压电性能;该体系陶瓷的组分在较大范围内变化时(如当y=z=0时,x=0～0.02;当x=z=0时,y=0～0.01;以及当x=y=0时,z=-0.01～0.005),仍然能保持d33>200pC/N和kP>40%这样较好的性能。上述结果不仅有利于在研究中材料制备工艺的重复,而且有利于当材料在器件应用时所面临的规模化生产。

Effect of nonstoichiometry on the phase transitions and properties of(K0.465Na0.465Li0.07)(Nb0.95Sb0.05)O3 lead-free piezoelectric ceramics

The(K0.465+xNa0.465+yLi0.07)(Nb0.95-zSb0.05)O3(with x,y and z varying from-0.01 to 0.02) ceramics were prepared by conventional technique and the effect of nonstoichiometry on the phase transitions and piezoelectric properties of the ceramics were studied.The results reveal that the ceramics with stoichiometric composition have perovskite structure with tetragonal phase;the excess or deficiency of K or Nb component cannot change the symmetry of the ceramics in experimental composition range,however,the excess of Na component will lead to the increase of TO-T of the ceramics above room temperature and the TO-T increase with y in the range concerned;the volatilization loss of the alkaline K or Na can be compensated by adding about 0.5mol% of K or Na content and enhanced piezoelectric properties are obtained;and the ceramics still have such promising piezoelectric properties d33>200pC/N and kP>40% even with composition deviation from designed one(x=0-0.02 when y=z=0,y=0-0.01 when x=z=0,and z=-0.01-0.005 when x=y=0).These results are much favorable for the experimental work and/or for the mass production when the materials are adopted for devices applications.