• Title/Summary/Keyword: $BaTiO_{3}$

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Microstructure and Microwave Dielectric Properties of Glass $(La_2O_3-B_2O_3-TiO_2)$/Ceramic Composites ($(La_2O_3-B_2O_3-TiO_2)$ 세라믹 조성에서의 미세 조직 과 마이크로 유전체 특성)

  • Jung, Byung-Hae;Hwang, Seong-Jin;Han, Tae-Hee;Kim, Hyung-Sun
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2003.11a
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    • pp.138-138
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    • 2003
  • Low temperature co-fired ceramic (LTCC) technology offers significant benefits over the other established packaging technologies for high density, high microwave frequency, and fast signal application. Most conventional electroceraramics do not meet the basic requirements in respect of sinterability for LTCC technology. Attention is, therefore, focused on the role of glasses because of the capability they supply with lower sintering temperatures. In this study, commercial ceramic (MBRT-90) in the system BaO-N $d_2$ $O_3$-Ti $O_2$ (BNT: 40 ~ 80 wt%) and L $a_2$ $O_3$- $B_2$ $O_3$-Ti $O_2$ glass (LBT;60 ~ 20 wt%) were prepared. These glass/ceramic composites were evaluated for sintering behavior, phase evaluation, densities, interface reaction, crystallinity, microstructure and microwave dielectric properties. It was found that the addition LBT glass frits significantly lowered the sintering temperature to below 90$0^{\circ}C$ and as temperature increased (750~90$0^{\circ}C$) densification developed dynamically which was meant to be as over 95% of relative density. It is supposed that in the microstructure, the grain size was increased accompanying with the formation of different phases such as LaB $O_3$ and Ti $O_2$ under the condition of increasing sintering temperature. The sintered bodies represented applicable dielectric properties, namely 20 ~ 40 for $\varepsilon_{{\gamma}}$, ~ 10000 GHz for Q* $f_{0}$ and 10~80 ppm/$^{\circ}C$ for $\tau$$_{f}$. The results suggest that the composite is one of feasible candidates for the microwave use in LTCC technology.y.e use in LTCC technology.y.

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Petrology of the Cretaceous Volcanic Rocks in the Hampyeong Area (함평지역 백악기 화산암류에 대한 암석학적 연구)

  • Cho, Dong-Hyun;Yun, Sung-Hyo;Koh, Jeong-Seon
    • The Journal of the Petrological Society of Korea
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    • v.18 no.2
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    • pp.93-114
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    • 2009
  • Lithological and petrochemical characteristics and tectonic setting of the Cretaceous volcanic rocks in Hampyeong area located in the southwestern part of Okchon Zone, were studied by field survey and petrochemistry of major, trace, and rare earth elements. The $SiO_2$contents of the volcanic rocks range from 50.8 to 77.2wt.%. With increasing $SiO_2$, $Al_2O_3$, $Fe_2O_3\;^T$, $TiO_2$, MnO, CaO and MgO contents decrease and $K_2O$content increase, but $Na_2O$content is scatter to the trend. According to TAS and AFM diagrams, the Cretaceous volcanic rocks are calc-alkaline series. On the discrimination diagram of $K_2O$versus $SiO_2$, the volcanic rocks belong to high-K rocks series. The trace element compositions and REE patterns of the volcanic rocks, characterized by a high LILE/HFSE ratio and enrichments in LREE, indicate that they are typical of continental margin arc calc-alkaline volcanic rocks associated with the subduction environment. The ratios of Ba/Ta and Ba/La indicate that they are associated with volcanic arc-related magmatism. The Cretaceous volcanic rocks in Hampyeong area might be located in the Eurasian continental margin, related to the Pacific type tectonic environment during the Cretaceous times.

A study on the measurement of thermophysical properties of ceramic dielectric materials by unsteady square wave pulse heating method (非定常方形波 펄즈 加熱에 의한 세라믹 誘電體의 熱物性値 測定에 관한 硏究)

  • 차경옥
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.12 no.1
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    • pp.152-162
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    • 1988
  • In recent years, attention has been paid to the ceramic material next to metals and plastics due to its inherent characteristics, i.e., good hardness, resistance to heat and corrosion. Recently, various kinds of ceramic dielectrics have been developed for application in industry. It is of prime importance to know the thermophysical properties for wider use of these new materials. However, no extensive effort has been made for systematic measurement of the properties. In this paper, the dielectric constant of five different kinds of ceramic dielectrics ware measured. We call these samples as MgO.SiO$_{2}$, MgTiO$_{3}$, TiO$_{2}$, CaTiO$_{3}$, and BaTiO$_{3}$. Which are currently in commercial sue. The values of thermal dirrusivities, specific heats, and thermal conductivities of these ceramic dielectrics sere measured as a function of temperature ranging from room temperature to about 1300k.

The Reliability and Electric Properties of High Voltage Multilayer Ceramic Capacitor According to Dielectric Materials (유전체 원료에 따른 고압용 적층칩 캐패시터 신뢰성 및 전기적 특성)

  • Yoon, Jung-Rag;Park, Jung-Won
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2007.11a
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    • pp.21-22
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    • 2007
  • 내환원성을 가지는 (Ca,Sr)(ZrTi)$O_3$계 C0G 원료와 코어 쉘 구조를 가지는 $BaTiO_3$계 X7R 원료를 적용하여 고압용 적층 칩 캐패시터를 제작하여 내부전극 형상 및 원료에 따른 신뢰성 밑 전기적 특성을 연구하였다. C0G 특성의 원료는 X7R 원료에 비해 단위 두께당 내전압이 감소하는 경향이 적었으며 내전압 특성도 우수하게 나타났다. 또한, 내부 전극 설계에 있어 floating에 따른 영향은 C0G, X7R 특성 원료 모두 향상된 전기적 특성과 신뢰성을 가짐을 확인 할 수 있었다.

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A study on the radiation properties of Far-infrared and microstructure in PTC thermistor (PTC 서머스터의 원적외선 방사특성과 미세구조에 관한 연구)

  • 박춘배;송민종;강도열
    • Electrical & Electronic Materials
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    • v.6 no.4
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    • pp.311-317
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    • 1993
  • 발열체 소자에 있어서 발열체의 방사스펙트럼과 피가열체의 흡수스펙트럼을 일치시키는 문제는 효과적인 가열을 위하여 매우 중요한 연구과제이다. 본 연구는 재료의 합성기술과 열처리기술을 이용하여 PTC 서머스터의 R-T특성은 그대로 유지시키면서 원적외선 방사특성을 증대시키기 위한 것이다. 이를 위하여 BaTiO$_{3}$+1.67Al$_{2}$O$_{3}$+3.75SiO$_{2}$+1.25TiO$_{2}$을 기본조성으로 하고 여기에 첨가제로서 Sb$_{2}$O$_{3}$와 MnO$_{2}$를 선정하여 이의 첨가량과 소결온도 그리고 소결온도구배를 파라메터로한 시편을 제작하였으며 각 시편의 IR특성과 R-T특성등을 측정 검토한 결과 파장 4.5-14.5[.mu.m]범위에서 방사율 0.8이상의 고효율 원적외선 방사특성을 얻었다.

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Effects of Si doping on PTC Properties in $BaTiO_3$ thermistor sintered in reduced atmosphere and reoxididation ($SiO_2$ 함량에 따른 $BaTiO_3$계 써미스터의 PTC 특성 변화)

  • Baek, Seung-Gyeong;Hong, Youn-Woo;Shin, Hyo-Soon;Yeo, Dong-Hun;Kim, Jong-Hee;Nahm, Sahn
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2009.06a
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    • pp.157-157
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    • 2009
  • $BaTiO_3$를 기본조성으로 하는 PTC 써미스터는 Curie 온도이상에서 저항이 급격히 상승하는 반도성 전자세라믹스로서 degaussing 소자, 정온 발열체, 온도센서, 전류 제한 소자 등 상업적으로 폭넓게 사용되고 있다. 본 소자는 소결온도, 소결 및 열처리 분위기, 불순물, 첨가제 등의 제조공정상의 인자들과 기공률, 결정립 크기 등이 복합적으로 작용하여 PTCR 특성이 크게 영향을 받기 때문에 제조하기에 무척 까다로운 소자로 알려져 있다. 특히 과전류 보호 소자용으로 사용하기 위해서는 상온 비저항을 크게 낮추어야 하며 이에 대한 연구가 계속 진행되고 있다. 따라서 본 연구에서는 SiO2을 0.5~10 at%로 달리한 조성으로 환원 분위기에서 소결하고 공기 중에서 재산화 처리하여 재료의 PTC 특성에 어떠한 영향을 미치는지 분석하였다. 소정의 조성을 선택하여 $1180^{\circ}C{\sim}1240^{\circ}C$에서 2시간 동안 환원분위기에서 소결하고, $800^{\circ}C$에서 1 시간 공기 중에서 재산화 처리한 후 R-T 특성을 측정하여 SiO2 함량에 따른 PTC 특성을 분석하였다. 그 결과 SiO2의 함량이 증가할수록 상온 저항은 낮아지다가 3.0 at% 이상으로 첨가할 경우 급격히 상승하는 경향을 나타내었다. 특히 SiO2를 1.0~3.0 at% 일 때 우수한 PTC 특성을 가졌다. $1180^{\circ}C$에서는 소결 밀도가 낮아 상온 비저항이 크게 높았지만, $1200^{\circ}C{\sim}1220^{\circ}C$에서는 정상 입성장이 나타나면서 일반적인 PTC 특성을 가졌지만, $1240^{\circ}C$ 이상에서는 공정 액상이 형성되어 비정상 입성장이 일어나 상온 비저항이 크게 낮아졌다. 한편 점핑비-log(Rmax/Rmin)는 SiO2 함량이 증가할수록 높아지다가 3.0 at% 이상에서는 낮아짐을 확인하였다.

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A study on the single buffer layers for the application of $YBa_{2}$$Cu_{3}$$O_{7-\delta}$ coated conductors (Y$Ba_{2}$$Cu_{3}$$O_{7-\delta}$ coated conductors의 응용을 위한 단일완충층에 대한 연구)

  • ;;;Donggi Shi
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2003.10a
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    • pp.120-122
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    • 2003
  • BaZrO$_3$and SrTiO$_3$(STO) thin films were Pulsed laser deposited on biaxially textured Ni and Ni-W alloy substrates to be used as single buffer layer for coated conductor. The texture of the films were analysed using the GADDS (general area detector diffraction system). Both films deposited on the metal tape were strongly (001) oriented, and in-plane textured (Δø (BZO) =9$^{\circ}$, Δø (STO) = 10$^{\circ}$).

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Geochemical Characteristics of Stream Sediments Based on Bed Rocks in the Naju Area, Korea (기반암에 따른 나주지역 하상퇴적물의 지구화학적 특성)

  • Park, Young-Seog;Kim, Jong-Kyun;Jung, Young-Hwa
    • Journal of the Korean earth science society
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    • v.27 no.1
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    • pp.49-60
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    • 2006
  • The purpose of this study is to investigate geochemical characteristics for stream sediments in the Naju area. We collected 139 stream sediments samples from primary channels. Samples were dried slowly in the laboratory and chemical analysis was carried out using XRF. ICP-AES and NAA. In order to investigate geochemical characteristics, the geological groups categorized into granitic gneiss area, schist area, granite area, arenaceous rock area, tuff area, andesite area, and rhyolite area. Average contents of major elements for geological groups are $SiO_2\;58.37{\sim}66.06wt.%,\;Al_2O_3\;13.98{\sim}18.41wt.%,\;Fe_2O_3\;4.09{\sim}6.10wt.%,\;CaO\;0.54{\sim}1.33wt.%,\;MgO\;0.86{\sim}1.34wt.%,\;K_2O\;2.38{\sim}4.01wt.%,\;Na_2O\;0.90{\sim}1.32wt.%,\;TiO_2\;0.82{\sim}1.03wt.%,\;MnO\;0.09{\sim}0.15wt.%,\;P_2O_5\;0.11{\sim}0.18wt.%$. According to the comparison of average contents of major elements, $Al_2O_3\;and\;K_2O$ are higher in granitic gneiss area, $Fe_2O_3,\;CaO,\;P_2O_5$ are higher in tuff area, MgO and $TiO_2$ are higher in andesite area, $Na_2O_$ is higher in rhyolite area, $SiO_2$, and MnO are higher in arenaceous rock area. Average contents of minor and rare earth elements for geological groups are $Ba\;1278{\sim}1469ppm,\;Be\;1.1{\sim}1.5ppm,\;Cu\;18{\sim}25ppm,\;Nb\;25{\sim}37ppm,\;Ni\;16{\sim}25ppm,\;Pb\;21{\sim}28ppm,\;Sr\;83{\sim}155ppm,\;V\;64{\sim}98ppm,\;Zr\;83{\sim}146ppm,\;Li\;32{\sim}45ppm,\;Co\;7.2{\sim}12.7ppm,\;Cr\;37{\sim}76ppm,\;Cs\;4.8{\sim}9.1ppm,\;Hf\;7.5{\sim}25ppm,\;Rb\;88{\sim}178ppm,\;Sc\;7.7{\sim}12.6ppm,\;Zn\;83{\sim}143ppm,\;Pa\;11.3{\sim}37ppm,\;Ce\;69{\sim}206ppm,\;Eu\;1.1{\sim}1.5ppm,\;Yb\;1.8{\sim}4.4ppm$. According to the comparison of average contents of minor and rare earth elements for geological groups, Pb, Li, Cs, Hf, Rb, Sb, Pa, Ce, Eu, and Yb are higher in granitic gneiss area; Ba, Co, and Cr in schist area; Nb, Ni, and Zr in arenaceous rock area; Sr in tuff area: and Be, Cu, V, Sc, and Zn are such in andesite area.

Thermally Stimulated Current Analysis of (Ba, Sr)TiO$_3$ Capacitor ((Ba, Sr)TiO$_3$ 커패시터의 Thermally Stimulated Current분석)

  • Kim, Yong-Ju;Cha, Seon-Yong;Lee, Hui-Cheol;Lee, Gi-Seon;Seo, Gwang-Seok
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.38 no.5
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    • pp.329-337
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    • 2001
  • It has been known that the leakage current in the low field region consists of the dielectric relaxation current and intrinsic leakage current, which cause the charge loss in dynamic random access memory (DRAM) storage capacitor using (Ba,Sr)TiO$_{3}$ (BST) thin film. Especially, the dielectric relaxation current should be seriously considered since its magnitude is much larger than that of the intrinsic leakage current in giga-bit DRAM operation voltage (~IY). In this study, thermally stimulated current (TSC) measurement was at first applied to investigate the activation energy of traps and relative evaluation of the density of traps according to process change. And, through comparing TSC to early methods of I-V or I-t measurement and analyzing, we identify the origin of the dielectric relaxation current and investigate the reliability of TSC measurement. First, the polarization condition such as electric field, time, temperature and heating rate was investigated for reliable TSC measurement. From the TSC measurement, the energy level of traps in the BST thin film has been investigated and evaluated to be 0.20($\pm$0.01) eV and 0.45($\pm$0.02) eV. Based on the TSC measurement results before and after rapid thermal annealing (RTA) process, oxygen vacancy is concluded to be the origin of the traps. TSC characteristics with thermal annealing in the MIM BST capacitor have shown the same trends with the current-voltage (I-V) and current-time (I-t) characteristics. This means that the TSC measurement is one of the effective methods to characterize the traps in the BST thin film.

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