Low temperature sintering of high performance KNN-based lead-free piezoelectric ceramic using BCBM frit as sintering aid

High performance lead-free (K0.49Na0.51)0.98Li0.02(Nb0.77Ta0.18Sb0.05)O3 + 0.5 mol%BaZrO3 piezoelectric ceramic was selected as base material, while BaO-CuO-B2O3-MnO2 frit was used as sintering aid to lower the sintering temperature. The effect of BaO-CuO-B2O3-MnO2 frit doping amount on the sintering behavior, structure and electrical properties of the ceramics was investigated. The optimal sintering temperature of the ceramics decreased with the increase of frit doping amount. The ceramic with frit doping amount of 1.0 wt.%, sintered at a reduced temperature of 1100°C, exhibited optimal electrical properties as follows: piezoelectric constant d 33 = 345 pC/N, planar electromechanical coupling coefficient k p = 44.5 %, mechanical quality factor Q m = 135, dielectric constant e 33 = 1210, and dielectric loss tanδ = 0.018. Together with its relatively high T c = 195°C, this ceramic was an excellent candidate for replacing the lead-based piezoceramics in practical applications.