Dielectric and Piezoelectric Properties of CeO2-Added Nonstoichiometric (Na0.5K0.5)0.97(Nb0.96Sb0.04)O3 Ceramics for Piezoelectric Energy Harvesting Device Applications

In this study, nonstoichiometric (K0.5Na0.5)(0.97)(Nb-0.96 Sb-0.04)O-3 ceramics were fabricated and their dielectric and piezoelectric properties were investigated according to the CeO2 addition. In this ceramic composition, CeO2 addition improved sinterability, electromechanical coupling factor k(p), mechanical quality factor Q(m), piezoelectric constant d(33), and g(33). At the sintering temperature of 1100 degrees C, for the 0.2wt% CeO2 added specimen, the optimum values of density = 4.359 g/cm(3), k(p) = 0.443, Q(m) = 588, epsilon(r) = 444, d(33) = 159 pC/N, and g(33) = 35 x 10(-3) V.m/N, were obtained. A piezoelectric energy harvesting device using 0.2wt% CeO2-added lead-free (K0.5Na0.5)(0.97)(Nb0.96Sb0.04)O-3 ceramics and a rectifying circuit for energy harvesting were fabricated and their electrical characteristics were investigated. Under an external vibration acceleration of 0.7g, when the mass, the frequency of vibration generator, and matching load resistance were 2.4 g, 70 Hz, and 721 Omega, respectively, output voltage and power of piezoelectric harvesting device indicated the optimum values of 24.6 mV(rms) and 0.839 mu W, respectively-suitable for application as the electric power source of a ubiquitous sensor network (USN) sensor node.