Microstructure, electrical properties and temperature stability in Bi0.5Na0.5Zr0.95Ce0.05O3 modified R-T phase boundary of potassium-sodium niobium lead-free ceramics

(1-x)K0.48Na0.52Nb0.95Sb0.05O3-xBi(0.5)Na(0.5)Zr(0.95)Ce(0.05)O(3) [(1 - x) KNNS-xBNZC] lead-free piezoelectric ceramics, with doping ratio of x ranging from 0 to 0.05, were synthesized by the conventional solid state sintering method. The phase transition behavior, microstructure and piezoelectric properties of (1 - x) KNNS-xBNZC ceramics were systematically investigated using XRD, SEM, and other devices with different doping amounts of BNZC. It was found that the piezoelectric properties of (1 - x) KNNS-xBNZC ceramics were improved obviously by adding the proper doping amount, 0.03 < x < 0.04, due to the coexistence of rhombohedral and tetragonal phases in the ceramics near room temperature. The piezoelectric constant d(33) of the ceramics first increased and then decreased when increasing the doping amount. A remarkably strong piezoelectricity was obtained in ceramics with a similar to 441 pC N-1 peak d(33) value. The excellent piezoelectric properties of (1 - x) KNNS-xBNZC ceramics with x = 0.034 were obtained: d(33) = 441 pC N-1, k(p) = 0.44, Q(m) = 31, epsilon(r) = 2447, tan delta = 0.037, T-C = 215 degrees C, P-r = 15.7 mu C cm(-2) and E-C = 8.2 kV cm(-1). With the annealing temperature reaching 250 degrees C, the d(33) values of the ceramics were still greater than 330 pC N-1, which represents good temperature stability for the piezoelectric property. It is believed that such a material system is a very promising candidate for lead-free piezoelectric ceramics.