Effects of BaO on the structure and electrical properties of 0.95K0.5Na0.5(Nb0.94Sb0.06)O3–0.05LiTaO3 lead-free ceramics

Lead-free ceramics 0.95K0.5Na0.5(Nb0.94Sb0.06)O3?0.05 LiTaO3 + xmol%BaO (0 ? x ? 3.00) have been fabricated by an ordinary sintering technique. The results of x-ray diffraction show that the ceramic with a perovskite structure changes from tetragonal phase to pseudocubic phase by increasing the doping level of Ba, and the ceramics with 1.00 < x < 1.50 contain both the tetragonal and the pseudocubic phases at room temperature. After the doping with Ba, the grain growth is inhibited, the ferroelectric?paraelectric phase transition temperature (Tc) is decreased, and a diffuse phase transition is induced. The ferroelectric properties (Pr and Ec) show a slight decrease with increasing x up to 1.25, and then become weakened significantly. Because of the coexistence of the tetragonal and pseudocubic phases, the piezoelectric and dielectric properties of the ceramics with 1.00 < x < 1.50 are enhanced significantly. The ceramic with x = 1.25 exhibits the optimum properties: d33 = 261?pC?N?1, kP = 0.52, kt = 0.46, ?r = 1503, tan?? = 2.5% and Tc = 314??C. Our results have also demonstrated that the ceramics are non-deliquescent.

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