Synthesis and Properties of [Bi0.5(Na1-xAgx)0.5]1-yBayTiO₃ Piezoelectric Ceramics

A new group of ABO 3 -type lead-free piezoelectric ceramics, [Bi 0.5 (Na 1- x Ag x ) 0.5 ] 1- y Ba y TiO 3 , was developed, and the corresponding invention patent was submitted. The ceramics were synthesized by the conventional ceramic sintering technique using electronic grade raw materials, and the preparation techniques are very stable and convenient. The crystalline phase, microstructure and electric properties of the ceramics were also investigated. All the ceramics have high densities of about 5.70–5.84 g/cm 3 , which are more than 95% of the theoretical values. This system provides high piezoelectric performances: d 33 =168 pC/N, k p =0.31 when x =0.06, y =0.06. Moreover, the samples doped with a moderate amount of Mn could increase the mechanical quality factor Q m and reduce the dielectric loss tgδ simultaneously. The temperature dependence of piezoelectric properties measured show that at up to 180°C, d 33 can still remain 126 pC/N for [Bi 0.5 (Na 0.96 Ag 0.04 ) 0.5 ] 0.90 Ba 0.10 TiO 3 ceramics, which has a d 33 of 137 pC/N at room temperature.