Ceramic Department, Material and Energy Research Center (MERC)
Ceramic , Merc
Lead free potassium sodium niobate (KNN) piezoceramics were synthesized via conventional solid state sintering route. Nano and micron WO3 were separately added to KNN through ball-milling. Dielectric and piezoelectric properties of samples sintered in the temperature range of 1110°-1145°C were measured by precision LCR-meter and APC d33-meter devices. The results revealed that micron WO3 particles were effective in inhibiting the grain growth in KNN ceramics. Micron WO3-added KNN obtained much finer microstructure and the sintering process terminated at higher temperature compared to pure KNN and nano WO3-added KNN. Densification and electrical properties of KNN were considerably affected by using nano and micron WO3. Nano WO3-added KNN obtained its maximum density at lower sintering temperature compared to micron WO3-added KNN. With increasing the sintering temperature over optimum amounts, the density of both WO3-added KNN samples decreased due to the evaporation of alkalis. Finally, at 1125ºC KNNW3n showed d33, εr, tanδ, and Qm of 75 pC/N, 345, 2%, and 50, respectively. For KNNW3m sample at 1135ºC these values were 81 pC/N, 773, 3.3%, and 30, respectively.