Low-temperature sintering of K0.5Na0.5NbO3 lead free ceramics using nano CuO sintering aid

Lead free piezoelectric ceramic K0.5Na0.5NbO3 (KNN) was synthesized by conventional mixed oxide method. The effect of nano CuO additive as the sintering aid, on microstructure and electrical properties of pure KNN ceramics was investigated. Sintering process has a great impact on the piezoelectric properties of lead free piezoelectric ceramics. The results indicated that adding small amount of nano CuO sintering aid reduces the sintering temperature of lead free piezoelectric KNN ceramic to 900 °C, and also leads to excellent densification and proper microstructure. Samples characterization by X-ray diffraction represented that there are no secondary phases for KNN ceramics with CuO additive in the range of 0–2 mol%. The dielectric and piezoelectric properties are strongly modified by the amount of nano CuO additive. A high piezoelectric coefficient (d33) up to 130 pC/N and a dielectric loss <0.008 achieved for the sample with 0.5 mol% nano CuO, sintered at 900 °C for 4 h.