• ETRI Journal
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• v.33 no.1
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• pp.132-135
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• 2011

In this letter, we study the contemporary technologies for making ferroelectric films and the possibility of using the oscillator model of PZT-22 to analyze its ferroelectric properties. The material showed permittivity dispersion at 65 KHz and 88.5 KHz. We obtained relative attenuation ${\gamma}$, relaxation time ${\tau}$, and ${\varepsilon}_{max}$ of the material as 0.0008319, 0.5 s, and 603.438, respectively.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.546-549
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• 2006

A series of seismic tests was carried out using piezoelectric elements called "bender elements". A pair of bender elements can be used as a source and a receiver respectively to measure dynamic properties of concrete. The most suitable bender elements were developed and implemented to measure P wave velocity changes due to the cracks of a concrete beam caused by bending.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.684-688
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• 2001

The structural, piezoelectric and dynamic range characteristics of modified PbTi $O_3$ceramics were investigated as a function of Mn $O_2$addition. With the increase of Mn $O_2$addition, Curie temperature was decreased. As the increase of Mn $O_2$addition, mechanical quality factor ( $Q_{mt3}$) in the third over tone thickness mode was increased. Dynamic range in the third over tone thickness mode was also increased with the increase of Mn $O_2$addition. The composition ceramics added to 0.075wt% Mn $O_2$showed the best properties for SMD type resonator using third over tone thickness vibration in terms of high Curie temperature more than 31$0^{\circ}C$ and dynamic range of 49.38dB.B.

• Ceramist
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• v.23 no.1
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• pp.101-109
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• 2020

In this study, the phase transition behaviors of lead-free (Na_1/2Bi_1/2TiO₃)_(1-x)-(BaTiO₃)_x (NBT-BT) are investigated by using Brillouin spectroscopy. The elastic properties, sound velocity and absorption coefficient of NBT-BT are characterized as a function of temperature along different crystallographic axes. The temperature dependences of the elastic constants of NBT-BT near the morphotropic phase boundary are determined for the first time. The unpoled NBT-BT single crystals exhibits the typical relaxor behaviors, presenting broad acoustic and dielectric anomalies. The application of electric field induced discontinuous changes in the elastic properties at ~110℃, which indicates field-induced phase transition occurred. The electric field also changes the dielectric constant from more relaxor-like to ferroelectric-like dielectric behavior.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.10
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• pp.923-929
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• 2008

On the piezoelectric polymer, PVDF (poly vinylidene fluoride), the transparent conducting oxide (TCO) electrode material thin film was deposited by roll to roll sputtering process mentioned as a mass product-friendly process for display application. The deposition method for ITO Indium Tin Oxides) as our TCO was DC magnetron sputtering optimized for polymer substrate with the low process temperature. As a result, a high transparent and good conductive ITO/PVDF film was prepared. During the process, especially, the gas mixture ratio of Ar and Oxygen was concluded as an important factor for determining the film's physical properties. There were the optimum ranges for process conditions of mixture gas ratio for ITO/PVDF From these results, the doping mechanism between the oxygen atom and the metal element, Indium or Tin was highly influenced by oxygen partial pressure condition during the deposition process at ambient temperature, which gives the conductivity to oxide electrode, as generally accepted. With our studies, the process windows of TCO for display and other application can be expected.

• Journal of the Korean Ceramic Society
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• v.27 no.2
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• pp.187-194
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• 1990

Effects of MnO2 addition ranged from 0.0wt% to 5.0wt% on the microstructure and dielectric and piezoelectric properties of the Pb(Zr0.52 Ti0.48)O3 Ceramics have been investigated. The solubility limit of MnO2 in Pb(Zr0.52 Ti0.48)O3 is about 0.5wt%, and MnO2 as a valence state of Mn3+ is substituted for (Zr, Ti) lattice site in PZT solid-solution. The addition of MnO2 up to 0.5wt% in Pb(Zr0.52 Ti0.48)O3 brings increase of density, but decreased of grain size and tetragonality. Dielectric constant slightly decreases, but both coupling factor(Kp) and mechanical quality factor(Qm) increase with the addition of MnO2. However, excess amount of MnO2 addition more than 0.75wt% results in rapid decrease of resistance. Dielectric constant and tan $\delta$ increase due to the second phase and inhomogeneous Mn distribution.

• Journal of the Korean Ceramic Society
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• v.25 no.3
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• pp.268-276
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• 1988

Ba or La-Substituted lead niobate $(Pb_{1-x}Ba_x)_{1-y}La_{2y/3}Nb_2O_6$(PBLN), powders having needle shape are prepared by flux method using KCl and the effect of Ba or La substitution on morphology of obtained powders is examined. From these needle shape powders, grain-oriented ceramics are made by doctor-blade method and two-stage hot-pressing technique. The dielectric, piezoelectric and optical properties of the ceramics are also investigaated. Heating condition and the amount of substituted Ba or La have remarkable effects have large anisotropy in both permittivity and coupling factor depending on the pressing direction.

• Journal of Sensor Science and Technology
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• v.9 no.4
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• pp.327-333
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• 2000

Transversal SAW(Surface Acoustic Wave) filters of 340MHz were fabricated on piezoelectric substrates of the LN $128^{\circ}$ Y-X wafers. Both of spacing and width of IDT were $1.435{\mu}m$. For improving the power durability characteristics, titanium layer was inserted between aluminum electrode and piezoelectric substrate since it has high density, low thermal expansion coefficient, and good adhesive properties. Power durability was evaluated with respect to the thickness of inserted titanium layer and the temperature of heat treatment. Power durability is improved with increasing the thickness of the inserted titanium layer. Moreover, it is remarkably improved by heat treatment at the temperature of $300^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.45 no.11
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• pp.681-687
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• 2008

The sintering and electrical properties of the hydrothermal PSZT powders obtained by substituting 4, 6 and 8mol% Sr for Pb in PZT lattice structure were investigated. The lattice constant and particle size decreased in proportion to a quantity of Sr. The sintering properties of PSZT powders showed $7.754g/cm^3$ of sintered density and $4{\mu}m$ of grain size at sintering temperature of $1250^{\circ}C$. Curie temperature lowered gradually from $363.6^{\circ}C\;to\;319.2^{\circ}C$ and relative dielectric constants increased rapidly by a quantity of Sr. In comparison to PZT, moreover, the quality factor of PSZT was increased more than three times with increase of Sr mole ratio, and piezoelectric constant $(d_{31}\;and\;g_{31})$ was decreased. It was found that dielectric loss of PSZT was decreased by 0.574% which was half of PZT.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.255-258
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• 2000

In this study, the structural, dielectric and piezoelectric properties of Pb[(Sb$\sub$1/2/Nb$\sub$1/2/)$\sub$x/- (Ni$\sub$1/3/Nb$\sub$2/3/)$\sub$0.15-x/- (Zr,Ti)$\sub$0.85/]O$_3$(x = 0, 0.01, 0.02, 0.03, 0.04, 0.05) ceramics is investigated as a function of Pb(Sb$\sub$1/2/Nb$\sub$1/2/)O$_3$ (abbreviated PSN) substitution. With the increase of PSN substitution, the crystal structure is transO$_3$formed from the tetragonal phase to the rhombohedral phase and the grain size is decreased abruptly. The curie temperature is decreased with the PSN substitution. The dielectric constant is increased with the PSN substitution and maximum value of 2290 is obtained at 4mol% PSN. With the PSN substitution, the coercive field is increased and the remnant polarization is decreased. The Electromechanical coupling factor(k$\sub$p/) Is showed the highest value of 0.622 at lmol% PSN and the mechanical quality factor(Q$\sub$m/) is decreased abruptly with the PSN substitution.