Low Temperature Sintering and Properties of (K0.5Na0.5)NbO3 Piezoelectric Ceramics

Low temperature sintering of (K 0.5 Na 0.5 )NbO 3 was investigated using Bi 2 O 3 and Li 2 CO 3 as sintering aids. The microstructure of the sintered materials, together with the dielectric and piezoelectric properties were investigated. The optimal piezoelectric properties are obtained for the ceramics sintered at 900 °C for 5 h. The dielectric constant ($\varepsilon$), piezoelectric coefficient ($d_{33}$), and electromechanical coupling coefficient ($k_{\text{p}}$) show peak values of 877, 92 pC/N, and 0.27, respectively. These values are comparable to the values obtained for (K 0.5 Na 0.5 )NbO 3 ceramics sintered above 1100 °C. Besides, the underlying mechanism for abrupt change of the dielectric coefficient was explained in this work.