• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.8
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• pp.707-711
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• 2006

ZnO was doped up to 0.3 wt% for improving the electrical properties of lead-free $[Li_{0.04}(Na_{0.44}Ko_{0.52})-(Nb_{0.86}\;Ta_{0.10}\;Sb_{0.04})]O_3$ piezoelectric ceramics. The ceramics were fabricated with the conventional sintering processes. Crystal structure of the samples was tetragonal phase regardless of ZnO amount. However, the piezoelectric properties were varied with the ZnO amount. The electro-mechanical coupling factor $(k_p)$ was with the ZnO amount up to 0.2 wt% but decreased with the further addition. the maximum value of $k_p$ was 0.475. Density, piezoelectric charge constant and relative dielectric constant was also showed maximum value at 0.2 wt%. The maximum values are $4.75g/cm^3$, 275 pC/N, 1403, respectively. In contrast, the mechanical quality factor $(Q_m)$ was not varied with increasing the ZnO addition up to 0.2 wt% but rapidly increased at 0.3 wt%.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.4
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• pp.286-293
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• 2000

In this paper we investigated the structural dielectric and piezoelectric properties of 0.03Pb(Sb$\_$1/2//Nb$\_$1/2/)-0.97Pb(Zr$\_$0.495//Ti$\_$0.505/)O$_3$+0.5 wt% excess PbO + wt% MnO(X=0, 0.1, 0.3, 0.5, 0.7) ceramics to develop the high-power piezoelectric transformer. The piezoelectric transformers with dimension of 27.5$\times$27.5$\times$2.5［mm$^3$］were fabricated and their electrical properties were measured. Maxima of piezoelectric properties such as electro-mechanical coupling factor of 0.534 and mechanical quality factor of 1487 were obtained for the PSN-PZT with 0.3wt% MnO. voltage step-up ratios of piezoelectric transformers at 500［Ω］and no load were 0.78, 12.82, respectively. The maximum efficiency of piezoelectric transformer was 98.6% at 800［Ω］. While the 14W fluorescent lamp were driven by the piezoelectric transformer for more than 20［min］, increment of temperature in the piezoelectric transformer was 7［$\^{C}$］.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.1
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• pp.12-16
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• 2015

$(Na,K)NbO_3$-based piezoelectric ceramics were synthesized by a solid phase sintering method with various milling solvents. The solvents were varied with acetone, ethanol, and pure water to investigate the effect on the microstructure and electrical properties. NKN ceramics showed the maximum values of the relative density (94%), the mechanical quality factor (Qm: 78) and the electro-mechanical coupling factor ($k_p$: 0.25) at the ethanol solvent. It might mean that a solid phase sintering of the NKN piezoelectrics with a suitable solvent could improve the relative density and the piezoelectric properties.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.6
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• pp.463-467
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• 2011

In this study, thickness shear mode piezoelectric devices for AE sensor with excellent displacement and sensitivity characteristics were simulated using ATILA FEM program, and then fabricated. Displacement and electro mechanical coupling factors of the piezoelectric devices were investigated. The simulation results showed that excellent displacement and electromechanical coupling factor was obtained when the ratio of Length/Thickness was 1. The piezoelectric device of L/T= 1 exhibited the optimum values of fr= 150 kHz, displacement= $6.23{\times}10^{-8}$[m], $k_{15}$= 0.598. The results show that the thickness shear mode piezoelectric device is a promising candidate for the application of AE sensor piezoelectric device.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.164-164
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• 2009

A multilayer piezoelectric transformer(MPT) for step-down voltage was made by ceramic stack process. And then, the characteristics of piezoelectric transformer, such as resonance frequency, matching impedance, electro-mechanical coupling coefficient, voltage gain, heat generation and efficiency, are analyzed. The piezoelectric transformer consists of a lead zirconate titanate ceramic with a high electromechanical quality factor. The piezoelectric transformer, with a multilayered construction in the thickness direction, was formed with dimensions 15mm long, 15mm wide and 5mm thick.

• Journal of the Korean Ceramic Society
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• v.29 no.3
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• pp.183-188
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• 1992

The physical properties of 0.5PZT-0.5(PNN-PZN) ceramics have been investigated as a function of PZN content. A pyrochlore phase exists in the range of 600∼850$^{\circ}C$ and a stable perovskite phase appears above 850$^{\circ}C$. The piezoelectric properties (except electro-mechanical coupling factor) of 0.5PZT-0.5(PNN-PZN) ceramics showed almost linear relationships of PZN content within the range of 0.5PZT-0.5PNN system and 0.5PZT-0.5PZN system. The temperature dependence of piezoelectric constant, the electric field dependence of induced strain and a bend strength are improved by addition of PZN.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.9
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• pp.726-730
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• 2001

Temperature stabilities of dielectric constraints and resonant frequencies of the substrates are very important in piezoelectric ceramics oscillators and filters. In this study, it was investigated temperature stability of the length-extensional vibration mode of Pb(Zr$\_$y/Ti$\_$1-y/)O$_3$+x[wt%]Cr$_2$O$_3$ ceramics. The mode can be utilized in fabricating ultra-small 455 kHz IF devices. Addition of Cr$_2$O$_3$ in morphotrophic phase PZT decreased the variations of dielectric constant, electro-mechanical coupling factor k$\_$31/ and resonant frequency by thermal shock. As additive weight of Cr$_2$O$_3$increased, the temperature coefficient of resonant frequency changed from positive number to negative one. And the composition tith temperature coefficient of resonant frequency was shifted to the one with increased Cr$_2$O$_3$ additive weigh by thermal aging.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.11
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• pp.932-937
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• 2000

The length extensional vibration mode of a piezoelectric ceramic substrate is used in fabricating the ultra-small size resonators and filters. In general, the three side ratios of the rectangular substrate affect the resonant characteristics of the resonator using its length extensional vibration. In this paper, their relationships are studied. We know that changing the ratio of its length to its width makes possible to change the resonant frequency of the width vibration without degrading the length extensional vibration. And frequency constant for length extensional vibration becomes slightly small as the substrate thickness becomes thin, but it does not change as its length changes. Electro-mechanical coupling factor for length extensional vibration, k$\_$31/ does not change as its length changes within length/width$\geq$4, but it becomes small as its width increases.

• Steel and Composite Structures
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• v.46 no.4
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• pp.513-523
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• 2023

Buckling and post-buckling behaviors of geometrically perfect double-curvature shells made from smart composites have been investigated. The shell has been supposed to be exposed to transverse mechanical loading and magneto-electro-elastic (MEE) coupling. The composite shell has been made of two constituents which are piezoelectric and magnetic ingredients. Thus, the elastic properties might be variable based upon the percentages of the constituents. Incorporating small scale impacts in regard to nonlocal theory leads to the establishment of the governing equations for the double-curvature nanoshell. Such nanoshell stability will be shown to be affected by composite ingredients. More focus has been paid to the effects of small scale factor, electric voltage and magnetic intensity on stability curves of the nanoshell.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.3
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• pp.214-219
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• 2000

In this paper the structural dielectric and piezoelectric properties of Pb［(M $g_{1}$2// $W_{1}$2/)$_{x}$-(N $i_{1}$3//N $b_{2}$3/)$_{0.15-x-(Zr_{0.5})}$ $Ti_{0.5}$)$_{0.85}$］ $O_3$ (x=0.0~0.10) ceramic were investigated with the substitution of Pb(M $g_{1}$2// $W_{1}$2/) $O_3$. According to the substitution of Pb(M $g_{1}$2//W/1/2/) $O_3$ curie temperatures were slightly decrease due to the decrease of the tetrag-onality of crystal structure and coercive fields were decreased. Up to the substitution of Pb(M $g_{1}$2// $W_{1}$2/) $O_3$ 3mol%,remnant polarization dielectric constant piezoelectric constant were increased. Dielectric constant and electro-mechanical coupling factor( $k_{p}$, $k_{31}$ ) were appeared the highest value of 2230, 0.64, and 0.38 and piezoelectric constant( $d_{33}$ , $d_{31}$ ) was the largest value of 418, 202($\times$10$^{-12}$ /C/N), respectively, when the substitution amount of Pb(M $g_{1}$2// $W_{1}$2/N) respectively, when the substitution amount of Pb(M $g_{1}$2// $W_{1}$2/) $O_3$ was 3mol%.s 3mol%.%.