Cu/W Co-doped CaBi2Nb2O9 piezoelectric ceramics on structural and electrical properties

This article reports the significantly improved piezoelectric and ferroelectric properties of Cu/W co-doped Ca2Bi2Nb2-x(Cu1/4W3/4)xO9 (CBNCW-x, where 0 ≤ x ≤ 0.150) high Curie temperature lead-free piezoelectric ceramics. The crystal structure, microstructure, and electric properties of CBNCW-x ceramics have been systematically analyzed. The results show that ceramic samples have a bismuth layered structure of m= 2, which is a single-phase of CBN. The ceramic grains show the typical plate-like structure of the bismuth layer. Cu/W co-doped CBN ceramics increased the distortion of NbO6 octahedron, and significantly enhanced the piezoelectric constant and the remnant polarization. When x = 0.075, it shows better comprehensive properties with an excellent d33 of 13.8 pC/N, a high remnant polarization of 12.10 μC/cm2, the Tc of 918 °C, a dielectric loss value of 0.57%, and the Qm value of 7099. Moreover, CBNCW-0.075 ceramic simple maintains the d33 of 12.7 pC/N after annealing 900 °C for 30 min, which shows good high-temperature stability. It suggests that the Cu/W co-doped CBN ceramics have good application prospects in the high-temperature piezoelectric field.