• Korean Journal of Crystallography
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• v.12 no.3
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• pp.157-161
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• 2001

The observe relaxation phenomena and freezing behavior in Pb(Mg/sub ⅓/Nb/sub ⅔/O₃, relaxor ferroelectrics, weak electric-field properties as well as strong electric-field properties were investigated. The temperature dependence of the dielectric properties obtained using the low electric-field of 1 V/w was investigated. The dielectric properties obtained from the slope of the dielectric hysteresis loop and the temperature dependence of the pyroelectric properties were also investigated. When fitting all the experimental data with the Vogel-Filcher relation, a close agreement between the experimental data and equation was observed. The freezing temperature could be consistently calculated by the various methods.

• Journal of the Korean Ceramic Society
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• v.33 no.5
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• pp.556-562
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• 1996

In order to understand the electrostrictive behavior of Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) solid solutions the dielectric constants the electric-field-induced strains and the pyroelectric coefficients of (1-x)PMN-xPT (x=0.1-0.4) were investigated in the temperature range -50~20$0^{\circ}C$. For x=0.1~0.35 where the phase transi-tion is diffusive the strain has a maxima at the temperature of maximum pyroelectric coefficient (depolrizing temperature) rather than the temperature of maximum dielectric constant. For x=0.4 where the phase transition is relatively sharp the strain decreases monotonically as the temperature increases. Relationships among the above experimental results are discussed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.165-166
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• 2008

$(Ba_{0.6},Sr_{0.3},Ca_{0.1})TiO_3$ powders, which were prepared by sol-gel method using a solution of Ba-acetate, Sr-acetate and Ca-acetate and Ti iso-propoxide, were mixed with organic vehicle and the BSCT thick films were fabricated by the screen-printing techniques on high purity alumina substrates. The structural and dielectirc properties were investigated for various $Pr_2O_3$ and $Y_2O_3$doping contents. As a result of thermal analysis of $(Ba_{0.6},Sr_{0.3},Ca_{0.1})TiO_3$ powders, the exothermic peak was observed at around $670^{\circ}C$ due to the formation of the polycrystalline perovskite phase. All BSCT thick films, sintered at $1420^{\circ}C$ for 2h, showed the typical XRD patterns of perovskite polycrystalline structure. The average grain size of the specimens decreased with amount of $Pr_2O_3$ and $Y_2O_3$ contents.

• Proceedings of the Korean Ceranic Society Conference
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• 2000.04a
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• pp.129.1-129.1
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• 2000

• Journal of the Korean Ceramic Society
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• v.26 no.5
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• pp.670-676
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• 1989

The PbTiO3 is well known materials having remarkable ferroelectric, piezoelectric, and pyroelectric properties. PbTiO3 thin films with a perovskite structure were successfully fabricated on titanium substrate by chemical vapor deposition. These films were characterized according to composition, crystal structure, and electrical properties. Semi-quantitative compositional analysis of the deposited films was made by Auger Electron Spectroscopy(AES). The PbTiO3 film deposited on titanium substrate at the deposition temperature 75$0^{\circ}C$, the Ti(C2H5O)4 fraction 0.15, and O2 partial pressure 0.06atm, has a columnar structure and grows with(001) preferred orientation, and has stoichiometric composition. A clear dielectric transition and offset in the dc conductivity near the transition temperature(48$0^{\circ}C$) were observed in the deposited lead titanate film.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.491-491
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• 2011

Transparent and flexible electronic devices that are light-weight, unbreakable, low power consumption, optically transparent, and mechanical flexible possibly have great potential in new applications of digital gadgets. Potential applications include transparent displays, heads-up display, sensor, and artificial skin. Recent reports on transparent and flexible field-effect transistors (tf-FETs) have focused on improving mechanical properties, optical transmittance, and performances. Most of tf-FET devices were fabricated with transparent oxide semiconductors which mechanical flexibility is limited. And, there have been no reports of transparent and flexible all-organic tf-FETs fabricated with organic semiconductor channel, gate dielectric, gate electrode, source/drain electrode, and encapsulation for sensor applications. We present the first demonstration of transparent, flexible all-organic sensor based on multifunctional organic FETs with organic semiconductor channel, gate dielectric, and electrodes having a capability of sensing infrared (IR) radiation and mechanical strain. The key component of our device design is to integrate the poly(vinylidene fluoride-triflouroethylene) (P(VDF-TrFE) co-polymer directly into transparent and flexible OFETs as a multi-functional dielectric layer, which has both piezoelectric and pyroelectric properties. The P(VDF-TrFE) co-polumer gate dielectric has a high sensitivity to the wavelength regime over 800 nm. In particular, wavelength variations of P(VDF-TrFE) molecules coincide with wavelength range of IR radiation from human body (7000 nm ~14000 nm) so that the devices are highly sensitive with IR radiation of human body. Devices were examined by measuring IR light response at different powers. After that, we continued to measure IR response under various bending radius. AC (alternating current) gate biasing method was used to separate the response of direct pyroelectric gate dielectric and other electrical parameters such as mobility, capacitance, and contact resistance. Experiment results demonstrate that the tf-OTFT with high sensitivity to IR radiation can be applied for IR sensors.

• Applied Science and Convergence Technology
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• v.26 no.4
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• pp.70-73
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• 2017

The dielectric constant and loss of poling/non-poling was measured in the $Pb_{1-3x/2}La_x[(Mg_{1/3}Ta_{2/3})_{0.66}Zr_{0.34}]O_3$ samples. The addition of $La^{3+}$ to the $Pb_{1-3x/2}La_x[(Mg_{1/3}Ta_{2/3})_{0.66}Zr_{0.34}]O_3$ did not cause a large change in grain size. But the addition of $La^{3+}$ did show transition temperature, which shifted toward low temperature in the $Pb[(Mg_{1/3}Ta_{2/3})Zr]O_3$ systems. In addition, the dielectric and pyroelectric properties (${\varepsilon}{\sim}20000$, $p{\sim}0.03C/m^2K$) of this system using $La^{3+}$ have been greatly improved. Pyroelectrics $Pb_{0.97}La_{0.02}(Mg_{1/3}Ta_{2/3})_{0.66}Zr_{0.34}]O_3$ system was found to have a relatively high ferroelectric FOMs ($F_V{\sim}0.035m^2/C$, $F_D{\sim}0.52{\times}10^{-4}Pa^{-1/2}$) at room temperature. Spontaneous polarization showed a value of $0.27{\sim}0.35C/m^2$ in the composition added to $La^{3+}$. The piezoelectric constant ($d_{33}=350{\sim}490pC/N$) and electromechanical coupling factor ($k_P=0.25{\sim}0.35$) are obtained in $Pb_{1-3x/2}La_x[(Mg_{1/3}Ta_{2/3})_{0.66}Zr_{0.34}]O_3$ compositions with $La^{3+}$ dopant.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.690-693
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• 2002

This paper is concerned on method of simultaneous force(stress) and temperature sensing with PVDF film. PVDF film has piezoelectric and pyroelectric properties. Therefore, it senses changes of stress and temperature. But it's output is affected with two properties. Using different medium in a sensing element, this problem is solved. Two structures induce different equations that its solutions are changes of stress and temperature. This method and result is applicable in skin sensor that has complexity of material and structure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.246-247
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• 2007

(Ba,Sr,Ca)$TiO_3$ powders, which were prepared by sol-gel method using a solution of Ba-acetate, Sr-acetate and Ca-acetate and Ti iso-propoxide, were mixed with organic vehicle and the BSCT thick films were fabricated by the screen-printing techniques on high purity alumina substrates. The structural and dielectric properties were investigated for various $Dy_2O_3$ doping contents. As a result of thermal analysis, the exothermic peak was observed at around $670^{\circ}C$ due to the formation of the polycrystalline perovskite phase. All BSCT thick films, sintered at $1420^{\circ}C$ for 2h, showed the typical XRD patterns of perovskite polycrystalline structure and no pyrochlore phase was observed. The average grain size of the specimens decreased with.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.10
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• pp.796-801
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• 2001

Ferroelectric 0.05PZN-xPZT(90/10)-(0.95-x)PZT(10/90) (x=0.65, 0.85) specimens were fabricated by the solid-state reaction method, and especially PZT(90/10) and PZT(10/90) powders were derived by the sol-gel method. All specimens showed a uniform ferroelectric grain without the presence of the pyrocholre phase. Average grain size increased with an increased in sintering temperature, the values for the x=0.65 and x=0.85 specimens sintered at 125$0^{\circ}C$ were 14.4$\mu$m and 9.8$\mu$m, respectively. The dielectric constant and dielectric loss of the x=0.65 specimen sintered at 125$0^{\circ}C$ were 1247. 2.06%, respectively. The coercive field and the remanent polarization of x=0.65 and x=0.85 specimens sintered at 125$0^{\circ}C$ were 8.5kV/cm, 13$\mu$C/$\textrm{cm}^2$ and 17.2kV/cm, 28 $\mu$C/$\textrm{cm}^2$, respectively. The pyroelectric coefficient of the x=0.65 and x=0.85 specimens sintered at 125$0^{\circ}C$ were 5.64$\times$10$^{-8}$ C/$\textrm{cm}^2$K and 2.76$\times$10$^{-8}$ C/$\textrm{cm}^2$K, respectively.