Abstract In this study, to develop composition ceramics for energy harvesting devices, Pb(Ni1/3Nb2/3)O₃-Pb(Zr Ti)O₃ system ceramics substituted with Pb(Mg1/2W1/2)O₃ were manufactured by conventional mixed oxide method using Li₂CO₃ and Na₂CO₃ (LNCO) as sintering aids. Their microstructure and piezoelectric properties were also investigated. At the specimen sintered at 930℃, high values of piezoelectric properties appeared: the dielectric constant (εr) of 2,522 planar electromechanical coupling factor kp of 0.602, and k31 of 0.385, d31 = 229 [pC/N], g31 = 10.13 [mV.m/N], Qm of 70, respectively. These values were suitable for the application of devices such as energy harvesting devices and ultrasonic devices.
In this study, lead-free (Na0.465K0.465Bi0.07)(Nb0.93Ti0.07)O3-0.08MnO2 ceramics were fabricated by conventional mixed oxide method. Structural and electrical properties of lead-free (Na0.465K0.465Bi0.07)(Nb0.93Ti0.07)O3-0.08MnO2 ceramics with the variation of sintering temperature were investigated. As results of x-ray diffraction analysis, all specimens showed a typical polycrystalline perovskite structure without presence of the second phase. Sintered density increased with an increases of sintering temperature and the specimen sintered at 1,020℃ showed the maximum value of 4.5 g/cm3. The average grain size of the (Na0.465K0.465Bi0.07)(Nb0.93Ti0.07)O3-0.08MnO2 specimen sintered at 1,020℃ is about 0.83 μm. Electromechanical coupling factor, relative dielectric constant and dielectric loss of (Na0.465K0.465Bi0.07)(Nb0.93Ti0.07)O3-0.08MnO2 specimens sintered at 1,020℃ were 0.252, 741 and 0.043% respectively.
In this study, lead-free (K0.5Na0.5+X)(Nb0.96Sb0.04)O3+0.2mol%La2O3+1.2mol% K4CuNb8O23 (X= 0∼0.025) ceramics were fabricated by normal sintering method at 1060℃ for 5 h. Microstructures, piezoelectric and dielectric properties of specimens were investigated with special emphasis in the influence of Na excess addition. The grain size of specimen was slightly decreased with increasing Na content. In the 2 [mol%] Na excess addition of NKNS ceramics, density, electromechanical coupling factor, piezoelectric constant and electromechancal quality factor of specimen were found to reach the optimum values of 4.25 [g/cm3], 0.4357, 154.43 [pC/N] and 580, respectively.
Abstract: (K(0.5)Na(0.5)) (Nb(0.96)Sb(0.04)) O(3)+1.2 mol% K(4)CuNb(8)O(23) ceramics doped with iron oxide (Fe(2)O(3)) were prepared by a conventional mixed oxide method. And then, their piezoelectric and dielectric properties were investigated as a function of Fe(2)O(3) addition. X-ray diffraction studies reveal that Fe(3+) diffuses into the NKN lattices to form a solid solution with a pure perovskite structure at room temperature. At the sintering temperature of 1,060℃, when 0.2 mol% Fe(2)O(3) was doped, the piezoelectric constant (d(33)), electromechanical coupling factor (Kp), and mechanical quality factor (Qm) showed the excellent values of 131.67 pC/N, 0.436, and 696.36, respectively. Results show that Fe(2)O(3) deped (K(0.5)Na(0.5))(Nb(0.96)Sb(0.04))O(3)+1.2 mol% K(4)CuNb(8)O(23) lead-free piezoelectric ceramics are a promising lead free material for piezoelectric transformer applications.
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