• Title/Summary/Keyword: barium titanate

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The Effect of Adittives on the Sintering Properties of Barium Titanate Powder Prepared by Self-propagating High-temperature Synthesis (자전연소합성법에 의해 제조된 BaTiO3 분말의 소결특성에 미치는 첨가제의 영향)

  • Lim Sung-Jae;Shin Chang-Yun;Won Hyung-Il;Won Chang-Whan
    • Journal of Powder Materials
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    • v.13 no.2 s.55
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    • pp.129-137
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    • 2006
  • In this study, high purity fine $BaTiO_3$ powders were prepared by SHS (Self-propagating High-temperature Synthesis). We would examinate the study of sintering properties and characteristics as a function of temperature with various additives (binder, sintering agent). In separately binder addition, the green and sintered density of specimen were increased as binder content increases. The increased porosity resulted in fine grain size due to the inhibition of grain boundary moving. The $Al_{2}O_{3},\;TiO_{2}$ and MgO playa role of increasing dielectric constants at room temperature. These values were decreased at curie temperature. In case of $SiO_2$, the Curie temperature was decreased. In this study, a high dielectric ceramic capacitor material with temperature stability was synthesized by using various additives.

Synthesis and Optical Property of BaTiO3 Nanoparticles Using a Salt-assisted Ultrasonic Spray Pyrolysis Process (염 보조 초음파 분무 열분해 공정을 이용한 BaTiO3 나노입자의 합성과 광학적 성질)

  • Hwangbo, Young;Lee, Young-In
    • Journal of Powder Materials
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    • v.24 no.4
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    • pp.326-331
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    • 2017
  • The structural formation of inorganic nanoparticles dispersed in polymer matrices is a key technology for producing advanced nanocomposites with a unique combination of optical, electrical, and mechanical properties. Barium titanate ($BaTiO_3$) nanoparticles are attractive for increasing the refractive index and dielectric constant of polymer nanocomposites. Current synthesis processes for $BaTiO_3$ nanoparticles require expensive precursors or organic solvents, complicated steps, and long reaction times. In this study, we demonstrate a simple and continuous approach for synthesizing $BaTiO_3$ nanoparticles based on a salt-assisted ultrasonic spray pyrolysis method. This process allows the synthesis of $BaTiO_3$ nanoparticles with diameters of 20-50 nm and a highly crystalline tetragonal structure. The optical properties and photocatalytic activities of the nanoparticles show that they are suitable for use as fillers in various nanocomposites.

The Doping Effects of Intermediate Rare-earth Ions (Dy, Y and Ho) on BaTiO3 Ceramics (BaTiO3 세라믹 내 희토류(Dy, Y, Ho) 첨가 효과)

  • Park, Kum-Jin;Kim, Chang-Hoon;Kim, Young-Tae;Hur, Kang-Heon
    • Journal of the Korean Ceramic Society
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    • v.46 no.2
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    • pp.181-188
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    • 2009
  • The electrical property and microstructure in $BaTiO_3$ ceramics doped rare-earth ions with intermediate ionic size ($Dy^{3+},Ho^{3+},Y^{3+}$) were investigated. Microstructures have been characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). Incorporation of rare-earth ions to $BaTiO_3$ ceramics depended on their ionic radius sensitively. Compared to Ho and Y ions, Dy ions provide $BaTiO_3$ ceramics with the high rate of densification and well-developed shell formation, due to their high solubility in the $BaTiO_3$ lattice, but the microstructure of Dy doped $BaTiO_3$ ceramics is unstable at high temperature, because Dy ions could not play a role of grain growth inhibition, leading to diffuse into $BaTiO_3$ lattice continuously after completion of densification during sintering. Comparing electrical property and microstructure, it is shown that the reliability of capacitor improved by high shell ratio.

Synthesis of 100 nm BaTiO3 by Solid-state Reaction (고상법에 의한 100 nm BaTiO3 분말의 합성)

  • Kim, Jung-Hwan;Jung, Han-Seong;Cho, Joon-Yeob;Hong, Jeong-Oh;Kim, Young-Tae;Hur, Kang-Heon
    • Journal of the Korean Ceramic Society
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    • v.46 no.2
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    • pp.170-174
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    • 2009
  • $BaTiO_3$ powder was synthesized by the solid-state reaction of fine $BaTiO_3$ and $TiO_2$ raw materials. Fine grinding media of 50 and 300 microns were used for obtaining fine particulate mixture of $BaTiO_3$ and $TiO_2$ with high homogeneity. Effect of the size of grinding media on the synthesis mechanism of $BaTiO_3$ was discussed on the basis of the particulate morphology and thermogravimetry data for the mixture powders. By using the finer grinding media, $BaTiO_3$ was formed at the lower temperature and the particle size with the relatively narrower distribution could be obtained. $BaTiO_3$ powder with the average size of 100 nm was synthesized by the solid reaction in vacuum atmosphere.

Characteristics of AC Power Electroluminescent Device with the Double Dielectric Layers of Thin and Thick Barium Titanate Films ($BaTiO_3$ 박막과 후막의 2중 유전체로 구서된 AC 분산형 ELD의 특성)

  • Lee, Ju-Hyeon;Chae, Sang-Hoom;Bhattarai, B.B.;Kim, Hak-Soo;Park, Sung
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.14 no.8
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    • pp.679-687
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    • 2001
  • It is known that amorphous BaTiO$_3$ thin films have good insulating properties[1][2]. In this investigation, amorphous BaTiO$_3$ thin films were deposited by rf magnetron sputtering on thick BaTiO$_3$ films of AC powder EL devices which were fabricated by screen-printing. The electrical and optical properties of the EL devices were then investigated. Adding amorphous BaTiO$_3$ thin film, it showed that leakage current density was decreased. Especially, leakage current density was decreased more with he sample of 0.5-hour deposition than the sample of 4-hours deposition. This result led to the improvement of luminous efficiency by 11%. It could be concluded that proper amorphous BaTiO$_3$ thin film deposition improved the surface property of dielectric layer.

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Electrical properties of BST system thick films for microwave devices applications (초고주파 소자로의 응용을 위한 BST계 후막의 전기적 특성에 관한 연구)

  • Lee, Sung-Gap;Park, Choon-Bae;Han, Byoung-Sung;Park, Bok-Kee
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.08a
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    • pp.31-34
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    • 2003
  • ($Ba_{0.6-x}Sr_{0.4}Ca_x)TiO_3$ (BSCT) (x=0.10, 0.15, 0.20) powder, prepared by the sol-gel method, were mixed with organic vehicle and the BSCT thick films were fabricated by the screen-printing techniques on alumina substrates using the BSCT paste. The structural and the electrical properties were investigated for various composition ratio and sintering temperature. BSCT thick film thickness, obtained by four printings, was approximately 110 ~ 120 ${\mu}m$. The Curie temperature and dielectric constant at room temperature were decreased with increasing Ca content. The relative dielectric constant, dielectric loss and tunability of the BSCT(50/40/10) specimen, which was sintered at $1420^{\circ}C$ and measured at 1MHz, were about 910, 0.46% and 9.28% at 5kV/cm, respectively.

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Ferroelectric Domans in $BaTiO_3$ ($BaTiO_3$의 강유전성 분역)

  • 박봉모;정수진
    • Journal of the Korean Ceramic Society
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    • v.33 no.1
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    • pp.56-64
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    • 1996
  • A large amount of papers about the cubic-to-tetragonal phase transition the ferroelectric domain structures of the BaTiO3 were already reported but there exist still some needs to observe the domain behaviors directly. In this study the domain structures of the tinned plates prepared from ta single crystal grown by the TSSG technique were observed using a polarizing microscope TE and X-ray topography. The spatial relation be-tween the orientation states of domains was investigated and the effects of external stresses and electric fields on the behaviors of ferroelectric and ferroelastic domains were studied. All the 90$^{\circ}$walls cut off in the crystal are the wedge shaped lamellar domains and all the straight boundaries in the observed domain patte군 can be interpreted as the head-to-tail 90$^{\circ}$walls. The irregular overlapped boundaries commonly observed by using a polarizing microscope and X-ray topography are complex combinations of well-known 90$^{\circ}$walls and are domain walls were predominant and were stabilized after surface polishing. In the paraelectric phase region the domain walls vanished but the residual surface strain patterns could be seen at the same positions of the stabilized 90$^{\circ}$a-a walls in the tetragonal phase region, These stabilized walls resulted from the surface strain had a memory effect in domain formation during the repeated phase transitions and could notr be affected by an external electtric field.

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Precise pressure sensor using piezoelectric nanocomposites integrated directly in organic field-effect transistors

  • Tien, Nguyen Thanh;Trung, Tran Quang;Seol, Young-Gug;Lee, Nae-Eung
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.02a
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    • pp.500-500
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    • 2011
  • With recent advances in flexible and stretchable electronics, the development of physically responsive field-effect transistors (physi-FETs) that are easily integrated with transformable substrates may enable the omnipresence of physical sensing devices in electronic gadgets. However, physical stimuli typically induce whole sensing physi-FET devices under global influences that also cause changes in the parameters of FET transducers, such as channel mobility and dielectric capacitance that prevent proper interpretations of response in sensing materials. Extended-gate structures with isolated stimuli have been used recently in physi-FETs to demonstrate performances of sensing materials only. However, such approaches are limited to prototype researches since isolated stimuli rarely occur in real-life applications. In this report, we theoretically and experimentally demonstrated that integrating piezoelectric nanocomposites directly into flexible organic FETs (OFETs) as gate dielectrics provides a general research direction to physi-FETs with a simple device structure and the capability of precisely investigating functional materials. Measurements with static stimulations, which cannot be performed in conventional systems, exhibited giant-positive d33 values of nanocomposites of barium titanate (BT) NPs and poly (vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)).

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Structural and Dielectric Properties of BSCT Thick films with Various Sintering Temperature (소결온도에 따른 BSCT 후막의 구조적, 유전적 특성)

  • 이성갑;이영희;이상헌
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.16 no.4
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    • pp.304-310
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    • 2003
  • (Ba$\sub$0.6-x/Sr$\sub$0.4/Ca$\sub$x/)TiO$_3$(BSCT) (x=0.10, 0.15, 0.20) powder, prepared by the sol-Bel method, were mixed with organic binder and then BSCT thick films were fabricated by the screen printing techniques on alumina substrates using the BSCT paste. The structural and the dielectric Properties were investigated for various composition ratio and sintering temperature. The second phase appeared in BSCT(40/40/20) thick film sintered at 1450$^{\circ}C$. BSCT thick film thickness, obtained by four printings, was approximately 110∼120$\mu\textrm{m}$. The Curie temperature and dielectric constant at room temperature were decreased with increasing Ca content. The relative dielectric constant, dielectric loss and tunability of the BSCT(50/40/10) specimen, which was sintered at 1420$^{\circ}C$ and measured at 1MHz, were about 910, 0.46% and 9.28% at 5㎸/cm, respectively.

The Structure and Dielectric Properties of the (Ba,Sr)TiO$_3$ Thin Films with the Substrate Temperature (기판온도에 따른 (Ba,Sr)TiO$_3$ 박막의 구조와 유전특성)

  • 이상철;이문기;이영희
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.49 no.11
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    • pp.603-608
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    • 2000
  • $(Ba, Sr)TiO_{3}$[BST] thin films were fabricated on the Pt/TiO$_2$/SiO$_2$/Si substrate by the RF sputtering. The structure and dielectric properties of the BST thin films with the substrate temperature were investigated. Increasing the substrate temperature, The BST phase increased and barium multi titanate phases decreased. Increasing the frequency, the dielectric constant decreased and the dielectric loss increased. The dielectric constant and dielectric loss of the BST thin films deposited at 50$0^{\circ}C$ were 300 and 0.018, respectively at 1 kHz. The leakage current density of the BST thin films deposited at 50$0^{\circ}C$ was $10^{-9}$ A/$\textrm{cm}^2$ with applied voltage of 3V. Because of the high dielectric constant(300), low dielectric loss(0.018) and low leakage current($10^{-9}$ A/$\textrm{cm}^2$), BST thin films deposited at 50$0^{\circ}C$ is expecting for the application of DRAM.

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