Temperature-stable dielectric and piezoelectric properties of (K0.5Na0.5)NbO3-Bi(Cu0.75W0.25)O3 solid solutions

(1 − x)(K0.5Na0.5)NbO3-xBi(Cu0.75W0.25)O3 (abbreviated as KNN-BCW) [x = 0, 0.005, 0.01, 0.015, 0.02, 0.025] lead-free ceramics were fabricated by a solid state reaction method. The XRD analysis confirmed that Bi(Cu0.75W0.25)O3 has diffused into (K0.5Na0.5)NbO3 to fabricate a new solid solution with perovskite structure. As x = 0.01, the ceramics exhibited high relative permittivity (ε ∼ 1121), low dielectric loss (tanδ <2.8%). Especially, good thermal stability (Δε/ε150 °C ≤±15%) was obtained in a broad temperature range from 150 °C to 500 °C as x = 0.025. The results indicated that the addition of Bi(Cu0.75W0.25)O3 could enhance the dielectric properties of ceramics. The thermal aging behavior represented that the d33 was decreased gradually with increasing the measured temperatures.