Effect of BBS ‐Based Frit on the Low Temperature Sintering and Electrical Properties of KNN Lead‐Free Piezoceramics

Using BaO – B ₂ O ₃ – SiO ₂ ( BBS )‐based frit as sintering aid, the K _0.49 Na _0.51 NbO ₃ ( KNN ) + x wt% BBS ( x = 1.0, 1.5, 2.0 and 2.5) lead‐free piezoelectric ceramics were successfully fabricated by solid‐state reaction method under low‐sintering temperature of 1000°C. The effect of BBS frit doping amount on the structure and electrical properties of the ceramics was investigated. The KNN ceramics with 1.5 wt% BBS frit showed optimal properties as follows: piezoelectric constant d ₃₃ = 108 pC /N, planar electromechanical coupling coefficient k _p = 41%, mechanical quality factor Q _m = 225, relative dielectric constant ε _r = 410, dielectric loss tan δ = 0.57% and Curie temperature T _c = 400°C. This ceramic sample should be a good lead‐free candidate for actuators or high temperature sensors application due to its ultra‐low tan δ , relatively high Q _m and T _c .