Studies on new systems of BNT-based lead-free piezoelectric ceramics

Several new systems of Bi0.5Na0.5TiO3-based lead-free piezoelectric ceramics were proposed based on the design of the multiple complex in the A-site of ABO(3) compounds. These ceramics were prepared by conventional ceramic techniques. The comparison of the piezo- and ferroelectric properties of these ceramics with those of the best properties of the Bi0.5Na0.5TiO3-based lead-free piezoelectric ceramics published recently shows that these ceramics of the new systems have better ferroelectric and piezoelectric performance, and better temperature characteristic of the properties. Among these materials, Bi-0.5(Na1-x-yKxLiy)(0.5)TiO3 possesses higher piezoelectric constant (d(33)=230.8 pC/N), higher electromechanical couple factor (k(p)=0.41), larger remanent polarization (P-r=40 mu C/cm(2)) and a better P-E hysteresis loop below 200 degrees C. Practical devices such as ceramic middle frequency filters and buzzers have been made by using these lead-free piezoelectric ceramics.