• Journal of the Korean Ceramic Society
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• v.52 no.1
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• pp.77-82
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• 2015

The effect of the electrode type on the dielectric and piezoelectric properties of $Pb(Mg_{1/3}Nb_{2/3})O_3-PbZrO_3-PbTiO_3$ (PMN-PZT) single crystals was investigated in an effort to improve their properties for various piezoelectric applications. First, three different types of PMN-PZT single crystals [PMN-PZT-A (piezoelectrically soft type; dielectric constant ~ 10,000), PMN-PZT-B (piezoelectrically soft type; phase-transition temperature between the rhombohedral and tetragonal phases ($T_{RT}$) ~ $145^{\circ}C$), PMN-PZT-C (piezoelectrically hard type; high mechanical quality factor ($Q_m$) ~ 1,000)] were fabricated using the solid-state single crystal growth (SSCG) method. Then, four different types of electrodes [sputtered Au, sputtered Cr/Au, sputtered Ti/Au, and fired Ag] were formed on the single crystals, and their dielectric and piezoelectric properties were measured. The single crystals with a sputtered Ti/Au electrode showed the highest dielectric and piezoelectric constants but the lowest coercive electric field ($E_C$). The single crystals with a fired Ag electrode showed the lowest dielectric and piezoelectric constants but the highest coercive electric field ($E_C$). This dependence on the type of electrode was most significant in the piezoelectrically hard PMN-PZT-C single crystals. However, the effects of the electrode type on the phase transition temperatures ($T_C$, $T_{RT}$) and dielectric loss were negligible. These results clearly demonstrate that it is important to select an appropriate electrode so as to maximize the dielectric and piezoelectric properties of single crystals in each type of piezoelectric application.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.7
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• pp.597-601
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• 2002

In this study, the structural, dielectric and piezoelectric properties of $Pb[(Ni_{1/3}Nb_{2/3})_x-(Mn_{1/3}Nb_{2/3})_{0.09-x}-(Zn_{0.505}Ti_{0.495)_0.91]O_3$ (x=0, 0.01, 0.02, 0.03, 0.04, 0.05) system ceramics were investigated to develop the composition ceramics for piezoelectric transformer. All the specimens were sintered at $1250^{\circ}C$ and its physical properties were measured, and the results are as follows : With increasing PNN substitution for PMN-PZT system, dielectric constant was increased and electro-mechanical coupling factor($k_p$) was increased to 0.62 at 5 mol% while mechanical quality factor(Qm) was decreased.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.10
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• pp.771-775
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• 2010

In this study, piezoelectric and dielectric properties of the $(Na_{0.5}K_{0.5})NbO_3-(1-x)(Bi_{0.5}Na_{0.5})TiO_3-xBaTiO_3$ [NKN-(1-x)BNT-xBT] ceramics were investigated. The lead-free NKN-(1-x)BNT-xBT ceramics were fabricated by a conventional mixed oxide method. The results indicate that the addition of $BaTiO_3$ significantly influences the sintering, microstructure, phase transition and electrical properties of NKN-BNT ceramics. A gradual change in the piezoelectric and dielectric properties was observed with the increase of BT contents. The dielectric constant, piezoelectric constant ($d_{33}$) and electromechanical coupling factor ($k_p$) increased at the morphotropic phase boundary (MPB). The $d_{33}$=184 pC/N, $k_p$=0.38, dielectric constant=1455 with dielectric loss value of less than 1% were obtained for the NKN-0.95BNT-0.05BT ceramics sintered at $1150^{\circ}C$ for 2h. These results demonstrate that the NKN-(1-x)BNT-xBT ceramics is an attractive candidate for lead-free piezoelectric materials.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.104-104
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• 2009

In this study, both structural, dielectric and piezoelectric properties of the NKN-0.96BNT-0.04BT ceramics were investigated. All samples of the NKN-0.96BNT-0.04BT ceramics were fabricated by conventional mixed oxide method with Pt electrodes. We report the improved dielectric and piezoelectric properties in the perovskite structure composed of the NKN, BNT and the BT ceramics. We investigated the effects of NKN, BT on the structural and electrical properties of the NKN-0.93BNT-0.07BT ceramics. The dielectric properties and piezoelectric properties of the NKN-0.93BNT-0.07BT ceramics were superior to those of single composition NKN, NKN-BNT and those values for the NKN-0.93BNT-0.07BT ceramics were 861 and 1.12%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1989.06a
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• pp.63-65
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• 1989

Piezoelectric BaTiO$_3$-polymer composite were investigated for dielectric and piezoelectric properties with the barium titanate active particle size. Under the condition of the same density and ceramic volume ratio of composite, the dielectric and piezoelectric constant of composite are increasing as the ceramic particle size in composite are increasing. The surface layer model was quoted to explain these phenomena in our system and experimentally confirmed. The connectivity parameter of modified cube model of composite was calculated from the dielectric constant variation as their particle size. The connectivity parameter X and Y were 77.8% and 98.9% respectively. It means that the barium titanate particle distribution in composite nearly approach to the parallel mode. It was experimentally confirmed that the surface layer has low dielectric and nonferroelectric properties. Dielectric constant and thickness of surface layer were calculated from the equivalent circuit of composite.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.10
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• pp.815-820
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• 2001

The piezoelectric properties of the PT-PZ-PNN system ceramics were investigated depending on the variati on of the grain size. The grain size was varied by sintering temperature, and additive. The effect of the grain size on the electrical, dielectric, and piezoelectric properties was studied with respect to the feasibility of the application for the piezoelectric transformer. Grain size increased as the PMW contents increased. The smaller the particle size used, the smaller the grain size obtained. Specimens are densily sintered. Dielectric and piezoelectric properties are not always improved in proportion to the grain sizes. When he particle size are fine and the grain size are increased properly with the optimum additives, the piezoelectric preperties have good values. the specimen sintered at 1200$\^{C}$ with PMW 2 mol% and MnO$\_$2/ 0.5wt% contents exhibited good piezoelectric properties for a piezoelectric transformer.

• The Korean Journal of Ceramics
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• v.1 no.1
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• pp.13-20
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• 1995

Effects of thermal annealing on the dielectric/piezoelectric properties of $Pb(Zn, Mg)_{1/3}Nb_{2/3}O_3-PbTiO_3$ ceramics (PZMNPT) with Zn/Mg=6/4) were examined across the rhombohedral/tetragonal morphotropic phase boundary (MPB). Both the relative dielectric permittivity ($\varepsilon$r)and the piezoelectric constant($d_33$)/electromechanical coupling constant ($k_p$)were increased by thermal annealing ($800^{\circ}$~$900^{\circ}C$) after sintering at $1150^{\circ}C$ for 1 hr. Based on the dielectric analysis using the series mixing model and the concept of a random distribution of the local Curie points, the observed improvements in the dielectric and piezoelectric properties of PZMN-PT were interpreted in terms of the elimination of PbO-rich amorphous intergranular layers(~1nm) induced by thermal annealing. A concrete evidence of the presence of amorphous grain-boundary layers in the unannealed (as-sintered) specimen was obtained by examining the structure of intergranular region using a TEM.

• Electrical & Electronic Materials
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• v.9 no.4
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• pp.351-356
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• 1996

The quartemary system ceramics 0.5[xPb(Zn$_{1}$3/Nb$_{2}$3/)O$_{3}$-(1-x)Pb(Ni$_{1}$3/Nb$_{2}$3/)O$_{3}$]-0.5[yPbTiO$_{3}$-(1-y) PbZrO$_{3}$ for piezoelectric actuators were prepared bv the were added to the raw materials up to 5 mole. Sintering temperature was varied form 1000.deg. C to 1200.deg. C. Sintering characteristrics, dielectric and piezoelectric properties were then investigated. Piezoelectric properties of sample prepared by the molten salt method were improved compared to those prepared by the conventional method. Addition of PZN shifted morphotropic phase boundary to more Zr-rich composition and decreased the piezoelectric properties.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.142-145
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• 1996

In this study, dielectric and piezoelectric properties of 0.5PNN-(0.5-x)PZN-xPZT system ceramics with PZT mole ratio were investigated. As the amount of PZT increases, curie temperature was increased. The maximum of dielectric and piezoelectric constant was shoun at 0.3 mole of PZT amount. As a results, we have found that the structure of ceramics with PZT 0.3 mole was morphotropic phase boundary.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.730-732
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• 1992

In this study, piezoceramics/polymer composites with 3-3 connectivity were made by BURPS(Burnout Plastic Sphere) technique with PZT ceramics and PMMA sphere(50 - 80${\mu}m$). And the dielectric and piezoelectric properties dependent on the PZT vol.% were investigated. The dielectric constant($K_{33}$) of 3-3 composites is increased almost linearly with increasing the PZT vol.%, while piezoelectric coefficient($d_{33}$) is slightly increased.