Microstructure, electrical properties and temperature stability in Bi 0.5 Na 0.5 Zr 0.95 Ce 0.05 O 3 modified R–T phase boundary of potassium-sodium niobium lead-free ceramics

(1 − x )K 0.48 Na 0.52 Nb 0.95 Sb 0.05 O 3 – x Bi 0.5 Na 0.5 Zr 0.95 Ce 0.05 O 3 [(1 − x )KNNS– x BNZC] 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– x BNZC 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– x BNZC 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 ∼441 pC N −1 peak d 33 value. The excellent piezoelectric properties of (1 − x )KNNS– x BNZC ceramics with x = 0.034 were obtained: d 33 = 441 pC N −1 , k p = 0.44, Q m = 31, ε r = 2447, tan δ = 0.037, T C = 215 °C, P r = 15.7 μC cm −2 and E C = 8.2 kV cm −1 . With the annealing temperature reaching 250 °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.