Electrical properties of CuO added-KNN ceramics and 1–3 Piezocomposites

In the present study, the effects of CuO addition on the properties of potassium sodium niobate (K_0.5Na_0.5)NbO₃ - KNN ceramics and fibers were reported. Bulk KNN samples were prepared by dry-pressing and KNN fibers were also obtained by a novel alginate gelation method. All samples have crystallized in pure orthorhombic perovskite phase. Addition of 1.5 mole% CuO caused grain growth, densification and formation of a liquid phase at the grain boundaries. Curie temperature has shifted to lower temperatures with increasing CuO ratio. Double hysteresis loops were observed for the 1.5 mole% CuO-added KNN. Piezeoelectric properties of d₃₃=120 pC/N, k_p=0.27 and Q_m=772 were obtained from the 1.5 mole% CuO-added KNN. 1-3 KNN fiber/epoxy composites were also prepared from CuO added KNN fibers, and dielectric constant and loss of 1-3 composite were 81 and 1%, respectively.