Insung Kim

EFFECT OF Nb SUBSTITUTION ON THE PIEZOELECTRIC AND DIELECTRIC PROPERTIES OF 0.95(K0.5Na0.5) NbO3-0.05Li (Sb1 − x Nb x )O3 CERAMICS

ABSTRACT In this study, lead-free 0.95(K0.5Na0.5)NbO3-0.05Li(Sb1 − x Nb x )O3 system ceramics were fabricated according to the amount of Nb substitution for Sb site of LiSbO3 ceramics and their dielectric and piezoelectric characteristics were investigated. With increasing the amount of Nb substitution, electromechanical coupling factor (kp), density and piezoelectric constant (d33) increased up to 1mol% Nb and decreased above 1mol% Nb. With increasing the amount of Nb substitution, dielectric constant linearly decreased and Curie temperature increased. At the 1mol% Nb substitution composition ceramics sintered at 1040°C, electromechanical coupling factor (kp), density, dielectric constant (ϵr), piezoelectric constant (d33) and Curie temperature (Tc) showed the optimal value of 0.41, 4.35 g/cm3, 789, 206 pC/N and 395°C, respectively for piezoelectric device application.

Dielectric and piezoelectric properties of Bi2O3 added (Pb,Ca,Sr)(Ti,Mn,Sb)O3 ceramics sintered at low temperature

In this study, in order to develop low temperature sintering ceramics for a thickness mode multilayer piezoelectric transformer, (Pb,Ca,Sr)(Ti,Mn,Sb)O3 ceramics were fabricated using Na2CO3, Li2CO3, MnO2, and Bi2O3 as sintering aids at 870, 900, and 930 °C. Their respective dielectric and piezoelectric properties were investigated according to the amount of Bi2O3 addition. At the sintering temperature of 900 °C, the optimum value was shown for the density of 6.94 g/cm3, thickness vibration mode electromechanical coupling factor (henceforth, kt) of 0.497, thickness vibration mode mechanical quality factor (henceforth, Qmt) of 3162, and dielectric constant (henceforth, er) of 209 for thickness mode multilayer piezoelectric transformer application.

Piezoelectric and Dielectric Characteristics of (Na,K)(Nb,Sb)O3 Ceramics Doped with CoO

In this study, in order to develop lead free piezoelectric ceramics which have excellent temperature stability and high sinteribility for low loss multilayer piezoelectric actuator application, (Na,K)(Nb,Sb)O3 ceramics were fabricated and their piezoelectric and dielectric properties were investigated as a function of the amount of CoO addition. CoO addition improved sinterability, electromechanical coupling factor kp, piezoelectric constant d33 and dielectric constant ϵr of the composition ceramics. At the 0.3 wt% CoO added composition, density, kp, d33, ϵr and phase transition temperature showed the optimum values of 4.30 [g/cm3], 0.41, 211 [pC/N], 751 and 155°C, respectively, for low loss multilayer piezoelectric actuator application.

Dielectric and Piezoelectric Characteristics of (Na,K)NbO 3 Ceramics System According to Sintering Time

In this study, were investigated as a variations of sintering times in order to improve dielectric and piezoelectric properties of lead-free piezoelectric ceramics. were used as sintering aids and the specimens were sintered during 3, 5, 7, 9 and 11 hours, respectively. At the specimen sintered during 7 hour, Electromechanical coupling factor (), density, dielectric constant (), piezoelectric constant () and curie temperature () of composition ceramics showed the optimal value of 0.450, 4.274 , 1007, 257 [pC/N] and , respectively.

Dielectric and piezoelectric properties of (K 0.5 Na 0.5 ) 0.97 (Nb 0.96 Sb 0.04 )O 3 ceramics according to the amount of CeO 2 addition

In this study, non-stoichiometric composition of lead-free (K<inf>0.5</inf>Na<inf>0.5</inf>)<inf>0.97</inf>(Nb<inf>0.96</inf>Sb<inf>0.04</inf>)O<inf>3</inf> ceramics were fabricated. And then, their dielectric and piezoelectric properties were investigated according to the CeO<inf>2</inf> addition. In this ceramic composition, CeO<inf>2</inf> addition improved sinteribility, electromechanical coupling factor kp, mechanical quality factor Q<inf>m</inf>, piezoelectric constant d<inf>33</inf> and g<inf>33</inf>. At the sintering temperature of 1100°C and 0.2wt% CeO<inf>2</inf> added specimen, the optimum values of density = 4.359g/cm³ kp = 0.443, Qm = 588, ε<inf>r</inf> = 444, d<inf>33</inf> = 158 pC/N, and g<inf>33</inf> = 40.4mVm/N, were obtained respectively. Taking into consideration above physical properties, it is considered that this composition is applicable to lead-free haptic piezoelectric actuators.

Dielectric and Piezoelectric Properties of 0.95(K 0.5 Na 0.5 )NbO 3 -0.05Li(Sb 0.8 Nb 0.2 )O 3 Ceramics according to the Amount of CuO Addition

In this study, In order to improve dielectric and piezoelectric properties of Lead-free piezoelectric ceramics, were investigated as a function of the amount of CuO addition. With increasing the amount of CuO addition, density was increased up to 0.4 wt.% CuO and then decreased above. And also, electro mechanical coupling factor () was decreased. At the 0.4 wt% CuO added specimen sintered at , , Qm, density, dielectric constant () and [pC/N] showed the optimal value of , 0.354, 305, 645, and 144 pC/N respectively.

ELECTRICAL PROPERTIES OF PIEZOELECTRIC TRANSFORMER USING PSN-PMN-PZT CERAMICS

ABSTRACT In this study, Pb(Sb1/2Nb1/2)O3-Pb(Mn1/3Nb2/3) O3-Pb(Zr0.49Ti0.51)O3 (abbreviated as PSN-PMN-PZT) composition ceramics was sintered at 1230∼1270°C for developing the composition for piezoelectric transformer. At the ceramic composition sintered at 1250°C, Density, electromechanical coupling factor (kp) and mechanical quality factor (Qm) showed the excellent values of 7.78[g/cm3], 0.59 and 1931, respectively, suitable for piezoelectric transformer application. The single layer Rosen-type piezoelectric transformers were also sintered at the sintering temperature of 1250°C and manufactured with the size of 48 × 10 × 2 mm3, respectively, using the composition ceramics. And then, their electrical properties were investigated according to the variations of frequency and load resistance. At the load resistance of 150 kΩ, the voltage step-up ratio of the transformers showed the maximum values at the vicinity of 68.4KHz. And also, at that load resistance, piezoelectric transformers showed the temperature rises of about 6°C at the output power of 5W. At transformer with high effective electromechanical coupling factor(keff) and high piezoelectric constant(d33), lower temperature increase was relatively appeared. And also, the piezoelectric transformer was reviewed for the voltage down of igniter type energy harvesting piezoelectric device.

DIELECTRIC AND PIEZOELECTRIC CHARACTERISTICS OF 0.07Pb (Mn1/3Nb2/3) O3 −0.10Pb (Ni1/3Nb2/3) O3− 0.83Pb(Zr0.48Ti0.52) O3 CERAMICS ACCORDING TO THE HEATING RATE

ABSTRACT In this study, in order to develop the composition ceramics for low loss multilayer piezoelectric actuator, 0.07Pb (Mn1/3Nb2/3) O3 −0.10Pb (Ni1/3Nb2/3) O3− 0.83Pb(Zr0.48Ti0.52) O3 (abbreviated as PMN-PNN-PZT) ceramics were fabricated using Li2CO3, Bi2O3 and CuO as sintering aids and according to variation of heating rate. And also, their dielectric and piezoelectric properties were investigated. At the heating rate of 700°C/h and sintering temperature of 900°C, density, electromechanical coupling coefficient (kp), mechanical quality factor (Qm), dielectric constant (ϵ r ) and piezoelectric constant (d33) of PMN-PNN-PZT ceramics showed the excellent values of 7.67 g/cm3, 0.58, 1199, 1560 and 380 pC/N, respectively for low loss multilayer piezoelectric actuator application.