• Journal of the Microelectronics and Packaging Society
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• v.2 no.1
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• pp.29-34
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• 1995

Glass 물질을 첨가하여 저온소결한(Ba, Sr, Ca) TiO3 세라믹 유전체의 전기 및 기계 적 특성을 조사하였다. PbO-ZnO-B2O3 계 glass를 첨가하여 소결온도를 135$0^{\circ}C$ to 105$0^{\circ}C$ With 4wt% of glass material the sintered specimen at 115$0^{\circ}C$ for 2hrs showed a dielectric constant over 8000 with low dissipation factor. As fired ceramic capacitor satisfied the Z5U( +10~ +85$^{\circ}C$; +22% ~-56%) specifications of the EIAs. The mechanical hardness and toughness of glass reacted ceramics slightly decreased but it hows higher hardness and toughness values than Lead perovskite dielectrics.

• Journal of Magnetics
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• v.8 no.2
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• pp.85-88
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• 2003

The magnetic and transport properties far single crystals of Ru-doped mono-layered manganites $La_{0.5}Sr_{1.5}-Mn_{1-x}Ru_xO_4$ (0$\leq$$\chi$$\leq$0.1) have been studied using neutron diffraction and magnetization measurements. Temperature dependent magnetization data reveal that with an increase in the Ru concentration the parent charge ordered antiferromagnetic state is gradually destroyed and new ferromagnetic phase evolves. In the low Ru-doped system spin glass behavior is apparent in low temperature region, which is confirmed by ac and do magnetization measurements. The competing magnetic interaction between Mn/Mn and Mn/Ru couples is the most likely cause of the spin glass transition.

• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.84-85
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• 2002

Recently doped perovskite manganites have renewed interest because they exhibit a variety of unique magnetic and electronic behaviors such as colossal magnetoresistance (CMR), percolative phase separation, spin/charge/orbital ordering, and so on. For this reason, fabrication of thin films with the best surface morphology and controlling their magneto transport properties is essential for making magneto-resistive devices. (omitted)

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.12
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• pp.576-580
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• 2006

The $(Sr_{0.85}Ca_{0.15})TiO_3(SCT)$ thin films were deposited on Pt-coated electrode $(Pt/TiN/SiO_2/Si)$ using RF sputtering method according to the deposition condition. The crystallinity of SCT thin films were increased with increase of deposition temperature in the temperature range of $100{\sim}500[^{\circ}C]$. The optimum conditions of RF power and $Ar/O_2$ ratio were 140[W] and 80/20, respectively. Deposition rate of SCT thin films was about $18.75[{\AA}/min]$ at the optimum condition. The composition of SCT thin films deposited on Si substrate is close to stoichiometry (1.102 in A/B ratio). The maximum dielectric constant of SCT thin film as obtained by annealing at $600^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.240-243
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• 1999

(Sr$\sub$0.85/Ca$\sub$0.15/)TiO$_3$thin films were deposited on Pt-coated TiO$_2$/SiO$_2$/Si wafer by the rf sputtering method. Experiments were conducted to investigate the electrical properties of SCT thin films with various top electrode. C-F and C-V measurements show that SCT thin films annnealed at 600$^{\circ}C$ have a larger capacitance than SCT thin films deposited at 400$^{\circ}C$ , and there is nearly no difference between top electrodes. I-V measurement show that Pt top electrode have a good leakage current density of < 10nA/$\textrm{cm}^2$,. making them suitable for DRAM application.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.244-247
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• 1999

The(Sr$\sub$0.85/Ca$\sub$0.15/) TiO$_3$(SCT) thin films are deposited on Pt-coated electrode(Pt/TiN/SiO$_2$/Si) using RF sputtering method. The composition of SCT thin films deposited on Si substrate at room temperature is close to stoichiometry(1.102 in A/B ratio). Also, SCT thin films deposited on Pt-coated electrodes have the cubic perovskite structure and polycrystalline state. The maximum dielectric constant of SCT thin films is obtained by annealing at 600[$^{\circ}C$].The dielectric constant changes almost linearly in temperature ranges of -80~+90[$^{\circ}C$].

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.85-86
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• 2006

A high Tc superconducting with a nominal composition of $Bi_2Sr_2Ca_2Cu_3O_y$ was prepared by the citarte method. The solid precursor produced by the dehydration of the gel at $120^{\circ}C$ for 12h is not in the amorphous state as expected but in a crystalline state. X-ray diffraction peaks of nearly the same angular position as the peaks of high Tc phase were observed in the precursor. After pyrolysis at $400^{\circ}C$ and calcination at $840^{\circ}C$ for 4h, the (001)peak of the high Tc phase was cleary observed. Experimental results suggest that the intermediate phase formed before the formation of the superconducting phase may be the most important factro in determining whether it is easy to form the high Tc phase or not, because the nucleation barriers of the two superconducting phase may be altered by the variation of the crystal structures of those intermediate phase.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.11b
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• pp.565-570
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• 1996

$^{32}$P는 순수한 $\beta$$^{-}$ 방출핵종(방출에너지 ＝ 1.71 MeV, 반감기 ＝ 14.3일)이며 의료용, 표지화합물 합성용, 유전공학 실험용 등으로 널리 사용되므로 고품질의 $^{32}$P의 수요에 부응하기 위해 감압증류법을 개발하였는 바 그 방법과 결과는 다음과 같다. 연구로 2호에서 중성자 조사된 황 표적을 감압 증류용기내에서 5~10 mmHg의 감압하에 200~30$0^{\circ}C$로 가열하여 황을 증류해 낸 다음 묽은 염산을 역류시켜 넣고 $^{32}$P 를 울궈냈다. 이 용액을 이온교환 수지로 정제하여 약 60 mCi/batch의 정제 $^{32}$P를 얻었다. 이온교환수지에 흡착되는 $^{32}$P의 방사능은 전체의 3% 미만이었고 여기에 흡착되는 불순 핵종은 $^{131}$ Ba, $^{85}$ Sr, $^{59}$ Fe, $^{65}$ Zn, $^{60}$Co이었다. 이 방법으로 얻은 $^{32}$P 최종제품은 핵종순도 >99%, 방사화학적 순도 >98%, 고형성분 함량 <1.2 mg/mL 이어서 그 품질이 우수함을 알 수 있었다.

• The Journal of the Petrological Society of Korea
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• v.2 no.2
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• pp.122-129
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• 1993

We report Rb-Sr whole rock, K-Ar and fission track mineral ages for the Chuncheon granite in the Precambrian Gyeonggi massif. The Rb-Sr whole rock define an age of $196{\pm}9$ Ma with an initial ratio of $0.7159{\pm}0.0006$, suggesting that the granitic magma might have been generated from crustal sources (S-type), or probably mixed mantle and crustal materials, and emplaced into the massif in the late Triassic or the early Jurassic. K-Ar mineral ages of hornblende, muscovite and biotite are ~210 Ma, ~180 Ma and 166-170 Ma respectively, and fission track zircon and apatite ages are 65-70 Ma, ~35 Ma respectively. These ages indicate that the granitic magma might have been emplaced at about 7 to 9 km from the paleosurface, and rapidly cooled down up to $300^{\circ}C$ until middle Jurassic (~170 Ma) with a rate of about $10^{\circ}C$/Ma, due to thermal difference between the magma and the wall rock. During middle Jurassic to late Cretaceous (about 170-70 Ma), the granite pluton is assumed to have uplifted to 4 to 6 km level under the paleosurface with a rate of 30 m/Ma and slowly cooled down with a rate of about $1^{\circ}C$/Ma owing to relatively slow denudation of the massif. In late Cretaceous to the present, the pluton might have more rapidly uplifted to the present level with a rate of 85 m/Ma and rapidly cooled down with a rate of about $3^{\circ}C$/Ma compared to those of middle Jurassic to late Cretaceous time because of extensive igneous activities accompanied by tectonism in the Gyeonggi massif.

• Journal of the Korean Ceramic Society
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• v.56 no.5
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• pp.497-505
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• 2019

Lanthanum-based transition metal cations containing perovskites have emerged as potential catalysts for the intermediate-temperature (600-800℃) oxygen reduction reaction (ORR). Here, we report a facile acetylacetone-assisted combustion route for the synthesis of nanostructured La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ (LSCF6428) cathodes for intermediate-temperature solid-oxide fuel cells (IT-SOFCs). The as-prepared powder was analyzed by thermogravimetry analysis-differential scanning calorimetry. The powder calcined at 800℃ was characterized by X-ray diffraction, scanning electrode microscopy, energy dispersive X-ray spectroscopy, and Brunauer-Emmett-Teller surface area measurements. It was found that the porosity of the air electrode significantly increased by utilizing the nanostructured LSCF6428 instead of commercial powder. The performance of a single cell fabricated with the nanostructured LSCF6428 cathode increased by 112%, from 0.4 to 0.85 W cm^-2, at 700℃. Electrochemical impedance spectroscopy showed a considerable reduction in the area-specific resistance and activation energy from 133.5 to 61.5 kJ/mol, resulting in enhanced electrocatalytic activity toward ORR and overall cell performance.