• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.05a
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• pp.5-8
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• 1994

In this paper, Dielectric and strain properties of (1-x-y)PMN-yPT-xST Ceramics hale been investigated as a function of the amount of SrTiO$_3$(ST). The SrTiO$_3$ content is ranged from 0.01-0.05(wt%). As the amount of ST is increased, dielectric constant has a maximun value at 0.05 mol% composition. The Curie temperature is decreased linearly with increasing ST composition and Polarization properties have been investigated. Coercive field and remnant polarization has a maximum value at 0.01mo1% composiion.

• Proceedings of the Korean Vacuum Society Conference
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• 1996.06a
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• pp.180-181
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• 1996

적외선 센서의 재료로 활용되고 있는 ppLT 박막(두께:8000~9000$\AA$)을 ppt/MgO(100)의 하부 구조상에 50$0^{\circ}C$ 및 $600^{\circ}C$에서 스퍼터링 증착하여 결정성 및 전기적 특성을 조사하였다. $600^{\circ}C$로 in-situ 성장된 ppLT 박막은 c-축(00l) 방향으로 배향 성장되었 고, 비유전상수(r)와 유전정접(tan)의 값이 10kHz~100kHz의 주파수에서 $\varepsilon$r≒35와 tan$\delta$≒ 0.01로 나타났다. 잔류분극량(2ppr)과 초전계수(${\gamma}$)는 상온부근에서 2ppr≒5$\mu$C/cm2, ${\gamma}$≒4$\times$ 10-8C/cm2.$^{\circ}C$로 비교적 양호한 초전박막의 전기적 특성을 나타내었다.

• Journal of the Korean Ceramic Society
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• v.55 no.2
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• pp.166-173
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• 2018

In order to investigate the effect of Mn on the dielectric and piezoelectric properties of PMN-PT [$Pb(Mg_{1/3}Nb_{2/3})O_3-PbTiO_3$], four different types of 71PMN-29PT samples were prepared using the solid-state single crystal growth (SSCG) method: (1) Undoped single crystals, (2) undoped polycrystalline ceramics, (3) Mn-doped single crystals, and (4) Mn-doped polycrystalline ceramics. In the case of single crystals, the addition of 0.5 mol% Mn to PMN-PT decreased the dielectric constant ($K_3{^T}$), piezoelectric charge constant ($d_{33}$), and dielectric loss (tan ${\delta}$) by about 50%, but increased the coercive electric field ($E_C$) by 50% and the electromechanical quality factor ($Q_m$) by 500%, respectively. The addition of Mn to PMN-PT induced an internal bias electric field ($E_I$) and thus specimens changed from piezoelectrically soft-type to piezoelectrically hard-type. This Mn effect was more significant in single crystals than in ceramics. These results demonstrate that Mn-doped 71PMN-29PT single crystals, because they are piezoelectrically hard and simultaneously have high piezoelectric and electromechanical properties, have great potential for application in fields of SONAR transducers, high intensity focused ultrasound (HIFU), and ultrasonic motors.

• Journal of the Korean Ceramic Society
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• v.27 no.7
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• pp.934-942
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• 1990

The quarternary system ceramics 0.5[yPb(Zn1/3Nb2/3)O3-(1-y)Pb(Ni1/3Nb2/3)O3]-0.5[xPbTiO3-(1-x)PbZrO3](PZN-PNN-PT-PZ) was fabricated by the columbite precursor method to obtain a stabilized perovskite structure and by conventional method to evaluate the efficiency of the former methd. Dielectric and piezoelectric properties were investigated and the stability of the perovskite phase was studied as a function of PZN and PT contents and firing temperature. In the samples prepared by the columbite precursor method, the pyrochlore phase, which is detrimental to both the dielectric and piezoelectric properties, was not observed in the absence of PZN, and electric properties were improved even when fabricated at low temperature. By adding PZN, some pyrochlore phase appeared and the morphotropic phase boundary of the samples shifted to more Zr-rich composition. The temperature dependence of piezoelectric constant decreased with the addition of PZN, due to the rising of the Curie point.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.400-403
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• 2004

The dielectric properties of $BaTiO_3/SrTiO_3$ multilayered thick films with printing times were investigated. $BaTiO_3/SrTiO_3$ thick films were deposited by Screen-printing method on alumina substrates. The obtained films were sintered at $1400^{\circ}C$ with bottom electrode(Pt) for 2hours. The structural and the dielectric properties were investigated for various printing times. The BST phase appeared in all of the $BaTiO_3/SrTiO_3$ mutilayered thick films. The $BaTiO_3/SrTiO_3$ multilayered thick film thickness, obtained by one printings, was $50{\mu}m$. The dielectric constant and dielectric loss of the $BaTiO_3/SrTiO_3$ multilayered thick film, obtained by five printings, were about 266, 0.8% at 1Mhz, respectively.

• Journal of the Korean Ceramic Society
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• v.39 no.9
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• pp.813-817
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• 2002

Magnetoelectric(ME) laminate composites of $Pb(Mg_{1/3}Nb_{2/3})O_3-PbTiO_3 (PMN-PT)$ and Terfenol-D were prepared by sandwiching single crystals of PMN-PT between Terfenol-D disks. The magnetoelectric voltage coefficient (dE/dH) of the composite was determined to be 10.30 V/cm${\cdot}$Oe, at 1 kHz and under a dc magnetic bias of 0.4 T. The value of dE/dH is ∼80 times higher than either that of naturally occurring magnetoelectrics or artificially-grown magnetoelectric composites. This superior magnetoelectric voltage coefficient is attributed to the high piezoelectric voltage constant as well as the high elastic compliance of PMN-PT single crystal and the large magnetostrictive response of Terfenol-D.

• Journal of the Korean Ceramic Society
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• v.45 no.3
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• pp.139-141
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• 2008

The piezoelectric properties of tetragonal 0.88Pb$(Zn_{1/3}Nb_{2/3)O_3-0.12PbTiO_3$ single crystals are characterized along the <111> direction, which composed the engineering domain configuration in the tetragonal phase. The <111>-oriented crystal possessed smaller $d_{33}$ values compared to the crystal along the <001> spontaneous polarization direction. Based on phenomenological theory, it is shown that the engineering domain configuration does not enhance the piezoelectric constant in tetragonal 0.88Pb$(Zn_{1/3}Nb_{2/3)O_3-0.12PbTiO_3$ single crystals. In addition, the electrostrictive coefficients of $Q_{12}=-0.03706m^4/C^2,\;Q_{11}=0.10765m^4/C^2,\;and\;Q_{44}=0.02020m^4/C^2$ of tetragonal 0.88PZN-0.12PT single crystals were calculated.

• Bulletin of the Korean Chemical Society
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• v.35 no.3
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• pp.925-928
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• 2014

A dye-sensitized solar cell (DSSC) was fabricated with a nanocrystalline $TiO_2$ film electrode on FTO glass, N719 dye, electrolytes (or $CsSnI_3$), and counter Pt electrode by incorporating it with single-walled carbon nanotubes (SWNTs). SWNTs were combined with $TiO_2$ film, $CsSnI_3$, Pt electrode, separately, and the SWNT-containing cell was compared with a pristine cell in cell performance. We also examined the performance change by pressing $TiO_2$ film, during cell fabrication, inside a high pressure chamber. Mostly, the change of conversion efficiency was compared for each cell, and an atomic force microscopy data were suggested to explain our results.

• Proceedings of the KIEE Conference
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• 1999.11a
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• pp.31-34
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• 1999

In the present study, we fabricated stoichiometric $(Ba_{1-x}Sr_x)TiO_3$ thin films at various substrate temperature and contents using of magnetron sputtering method on optimized Pt-based electrodes (Pt/TiN/$SiO_2$/Si). The substate temperature deposited at 200[ $^{\circ}C$], 400[$^{\circ}C$] and 600[$^{\circ}C$] and crystalline BST thin films show above 400[$^{\circ}C$]. Also, the composition of $(Ba_{1-x}Sr_x)TiO_3$ thin films deposited on Si wafer substrate at 400[$^{\circ}C$] were closed to stoichiometry($1.015{\sim}1.093$ in A/B ratio), but compositional deviation from a stoichiometry is larger as $SrCO_3$ is added. The drastic decrease of dielectric constant and increase of dielectric loss in $(Ba_{1-x}Sr_x)TiO_3$thin films is observed above 100[kHz]. V-I characteristics of $(Ba_{1-x}Sr_x)TiO_3$ thin films show the decrease of leakage current with the increase of $SrCO_3$ contents.

• Journal of the Korean Institute of Gas
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• v.13 no.2
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• pp.23-29
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• 2009

This study investigated sensitivity of the gas sensor to chemical weapons with the sensor material doped with catalysts. The nano-sized SnO2 powder mixed with metal oxides (TiO2) was doped with transition metals(Pt, Pd and In). Thick film of nano-sized SnO2 powder with TiO2 was prepared by screen-printing method onto Al2O3 substrates with platinum electrode and chemical precipitation method. The physical and chemical properties of sensor material were investigated by SEM/EDS, XRD and BET analyzers. The measured sensitivity to simulant toxic gas is defined as the percentage of resistance of value equation, [(Ra-Rg)/$Ra\;{\times}100$)], that of the resistance(Ra) of SnO2 film in air and the resistance(Rg) of SnO2 film in acetonitrile gas. The best sensitivity and selectivity of these thick film were shown with 1wt.% Pd and 1wt.% TiO2 for acetonitile gas at the operating temperature of $250^{\circ}C$.