Abstract:

In order to protect the environment and produce environmentally friendly materials and electronic devices, the research and development of lead-free piezoelectric ceramics have been carried out in recent years.Based on the current research on lead-free piezoelectric ceramics , this work investigates the preparation and propertiesof Li- and Ta-doped sodium potassium niobate (LNKNT) ceramics. XRD was then adopted to analyze the microstructure of the ceramics. The results show that (1) the Ta-doped LNKNT ceramics with a Ta composition (x)of 10% - 20% possess a monoclinic perovskite structure at room temperature ， then forms a complete solid solution when the Ta composition is 17 % and 20% ; (2) the monoclinic and tetragonal phases coexist near the monoclinictetragonal phase transition temperature , The Ta compositional dependences of dielectric properties and piezoelectric properties are discussed in this paper. When x = 17%， the piezoelectric coefficjent , plane electro-mechanical coupling factor and dielectric constant of the Ta-doped LNKNT ceramic are 235 pC/N 、0.49 and 1293.5 , respectively.50 , the ceramic , which has been used to prepare a lead-free piezoelectric buzzer , meets the requirements of industrial application.

Key words: lead-free piezoelectric ceramic, lithium, tantalum, sodium potassium niobate, X-ray diffraction, dielectric property, piezoelectric property