• Transactions on Electrical and Electronic Materials
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• v.4 no.4
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• pp.18-21
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• 2003

Sol-gel processing of $BaTiO_3$ ceramics doped with La(0.01-1.00 at. $\%$) were prepared from metal barium, titanium n-butoxide and lanthanum iso-propoxide. Characterization of the sol-gel-derived powder using XRD, SEM is also reported. The obtained results showed that insulator to semiconductor transition for highly donor-doped barium titanate was closely related to the incorporation of donor into the grains and to the resultant grain size, which were significantly affected by the sinterability of $BaTiO_3$ powders and sintering conditions used.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.10.1-10.1
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• 2011

Energy harvesting technologies converting external sources (such as thermal energy, vibration and mechanical energy from the nature sources of wind, waves or animal movements) into electrical energy is recently a highly demanding issue in the materials science community for making sustainable green environments. In particular, fabrication of usable nanogenerator attract the attention of many researchers because it can scavenge even the biomechanical energy inside the human body (such as heart beat, blood flow, muscle stretching, or eye blinking) by converging harvesting technology with implantable bio-devices. Herein, we describe procedure suitable for generating and printing a lead-free microstructured $BaTiO_3$ thin film nanogenerator on plastic substrates to overcome limitations appeared in conventional flexible ferroelectric devices. Flexible $BaTiO_3$ thin film nanogenerator was fabricated and the piezoelectric properties and mechanically stability of ferroelectric devices were characterized. From the results, we demonstrate the highly efficient and stable performance of $BaTiO_3$ thin film nanogenerator and the integration of bio-eco-compatible ferroelectric materials may enable innovative opportunities for artificial skin and energy harvesting system.

• Journal of the Korean Ceramic Society
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• v.33 no.11
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• pp.1231-1236
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• 1996

The electrode resistance of semiconducting PTC BaTiO3 ceramic material was studied in some detail. Comme-rical In-Ag paste In-Ga alloy and electroless plated Ni as well as evaporated Al were chosen as electrode. The contact resistance of electroded samples were measured by both dc resistivity and ac impedance analysis. The aging effect on contact resistance under cyclic loading from -1$0^{\circ}C$ to 85$^{\circ}C$ was also monitored for the prolonged period of time. In case of Al electroded samples the heat treatment and protective coating had effects on the stability against contact resistance degradation. It was also found that the samples with commercial In-Ag paste and electroless plated Ni electrode had good properties of contact resistance against aging.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.273-273
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• 2010

최근 들어 에너지 개발과 환경문제의 해결방안으로 열전발전 및 열전냉각에 많은 관심과 연구가 진행되고 있다. 열전소재의 특성 향상을 위해 열전성능지수를 높이기 위하여 나노 입자상을 열전소재 내에 분산하고자 하는 연구가 진행되었다. Grain 내에 나노 입자를 분산하기 위해서는 원료 입자에서부터 나노 입자가 열전소재 내에 분산되어야 하며 이것은 산화물 나노입자의 코어-쉘 형성으로부터 가능하다. 이 과정에서 나노 입자를 열전소재 내에 코어로 분산하기위한 나노입자의 합성 및 제어가 필수적이다. 본 연구에서는 용융염법을 이용한 BaTiO3 나노 일자를 합성하고 이들을 용매에 분산하는 것을 목표로 하였다. 염으로는 KCl, LiCl, NaCl 및 이들의 혼합 염을 사용하였으며 염의 청가량, 염의 종류, 반응온도 및 반응시간의 변화에 따라 BaTiO3 나노 입자를 합성하였다. 또한, 합성된 나노 입자의 입자크기와 응집 제어를 통해 나노입자들의 분산 상태를 확인해 보았다. 이 결과는 SEM, TEM, 입도측정기, XRD등의 측정 결과를 통하여 확인하고자 하였다.

• Journal of the Microelectronics and Packaging Society
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• v.1 no.2
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• pp.113-124
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• 1994

MOD법을 마이크로회로용 티탄산 바륨 콘덴서 박막형성에 적용하였다. Barium decanoate barium 2-ethylhexanoate titanium dimethoxy didecanoate 및 titanium dimethoxy di-2-ethylhexanoate와 같은 여러 가지 금속유기화합물들을 합성하고 동정한 다 음 공통용매에 대한 용해도를 시험하였다. 이금속유기화학물들 가운데 barium 2-ethylhexanoate와 titanium dimethoxy di-2-ethylhexanoate가 xylene-pyridine 혼합용매에 잘녹고 MOD법에 의한 BaTiO3 박막형성에 매우 안정한 조성을 이룸을 확인하였다. 이 조 성을 스핀코팅에 의하여 백금박과 실리콘 웨이퍼상에 금속유기화학물 막을 형성하고 최고 온도와 유지시간에 따라 소성하여 형성된 유전체 박막들의 전기전 특성을 측정하고 고찰하 였다.

• Journal of the Korean Ceramic Society
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• v.28 no.11
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• pp.926-934
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• 1991

The effect of aggregates on the forming and sintering behaviors of BaTiO3 was studied. Aggregates and deaggregates of fine crystallite were obtained by thermal decomposition of oxalate coprecipitates and subsequently crushing them with a press, respectively. Large voids formed by packing of aggregates were not easily eliminated despite the successive destruction of aggregates with increasing forming pressure. As a result, compacts of aggregates showed inhomogeneity with larger mid-pore size and broader pore size distribution with respect to those of deaggregates. This inhomogeneity caused differential shrinkage and consequental internal stress, which retarded densification. The differential sintering increased the size of mid-pores in the initial stage, and formed duplex structure composed of dense region with abnormally grown grains and porous region with fine grains. The driving force of this abnormal grain growth shown in the specimens of aggregates was attributed to the minimization of the elastic strain energy due to internal stress.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.6
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• pp.694-699
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• 1988

Optical phase conjugate mechanism and edge enhancement by degenerate four wave mixing (DFWM) in photorefractive material are described, and image reconstruction is perfromed sucessfully in BaTiO3 single crystal. Also, the edge enhancement is carried out in the crystal by the same DFWM geometry. But the intensities of three incident beams are inverted. Good quality of edge enhancement is observed in real-time (processing time 10 sec) with low incident light intensity (5.38mW/cm\ulcorner.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1560-1562
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• 1997

We have investigated the influence of Ca addition in the characteristics of the modified $BaTiO_3$ system. The specimens were fabricated with variations of Ca addition between 0mol% and 20mol%, and sintered in the $1350^{\circ}C$. It show that PTC effect was decreased with the increasing Ca mol% from 0 to 15 mol% and, In the analysis of SEM., the grain sizes were small with increasing Ca mol%.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.7
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• pp.1144-1151
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• 1994

The humidity-sensitive specimens-(BaS11T-S1xTCaS1xT)TiOS13T, x=0, 0.1, 0.2, 0.3, 0.4, 0.5-were fabricated by a solid-state reaction method which is easy in process control of microstructure and good in mass production, and their humidity-sensitive characteristics were examined. Ca inhibits grain growth and the open porosity increases with Ca substitution, and the specimens at x=0.5 show the best humidity sensitivity. Their humidity sensitivity is higher at the lower frequencies, and drift phenomenon in humidity sensitivity is exhibted with aging in the air, which disappears by a heat treatment. The electrical conduction with water adsorption is dominated by the ions, and the activation energy decreases with increasing relative humidity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.122-125
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• 1999

(Ba$_{0.6}$Sr$_{0.4}$)TiO$_3$(BST) thin films were fabricated with different deposition temperature and oxygen pressure by Pulsed Laser Deposition(PLD). Energy Dispersive Spectroscopy(EDS) proved that BST thin films prepared by PLD have almost the same stoichiometric composition as the BST target materials. This BST thin films were fully crystallized at $650^{\circ}C$, 300mTorr oxygen pressure and showed a maximum dielectric constant value of $\varepsilon$$_{t}$=684 and dielectric loss was 0.01 at 75$0^{\circ}C$, 300mTorr oxygen pressure.ssure.