In this study, lead-free (LiNaK)(NbTaSb)O 3 piezoelectric ceramics were fabricated on the basis of the amount of K 2 CO 3 addition, and their piezoelectric and dielectric properties were investigated by varying the amount of K 2 CO 3 addition and poling temperature. First, to achieve optimum poling conditions for manufactured specimens, the poling temperature was varied to be 0, 20, 50, 80, and 110 C. The optimum poling temperature was 20 C. It was found that 0.1 wt % K 2 CO 3 -added (Li 0:04 Na 0:44 K 0:52 ) (Nb 0:86 Ta 0:1 Sb 0:04 )O 3 ceramics exhibit excellent piezoelectric properties in an experiment performed on the basis of the amount of K 2 CO 3 addition. That is, a 0.1 wt % K 2 CO 3 -added specimen showed a large electromechanical coupling factor k p ¼ 0:494, a large piezoelectric constant d 33 ¼ 274 pC/N, and a high density of 4.65 g/cm 3 at the poling temperature of 20 C.

No abstract

No abstract

In this study, nonstoichiometric (Na(0.5)K(0.5))(0.97)(Nb(0.96)Sb(0.04))O(3) ceramics were fabricated and their dielectric and piezoelectric properties were investigated according to the CeO(2) addition. In this ceramic composition, CeO(2) 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°C, for the 0.2wt% CeO(2) added specimen, the optimum values of density = 4.359 g/cm(3), k(p) = 0.443, Q(m) = 588, ε(r) = 444, d(33) = 159 pC/N, and g(33) = 35 × 10(-3) V·m/N, were obtained. A piezoelectric energy harvesting device using 0.2 wt% CeO(2)- added lead-free (K(0.5)Na(0.5))(0.97)(Nb(0.96)Sb(0.04))O(3) ceramics and a rectifying circuit for energy harvesting were fabricated and their electrical characteristics were investigated. Under an external vibration acceleration of 0.7 g, when the mass, the frequency of vibration generator, and matching load resistance were 2.4 g, 70 Hz, and 721 Ω, respectively, output voltage and power of piezoelectric harvesting device indicated the optimum values of 24.6 mV(rms) and 0.839 μW, respectively-suitable for application as the electric power source of a ubiquitous sensor network (USN) sensor node.

No abstract