• Applied Science and Convergence Technology
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• v.26 no.2
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• pp.26-29
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• 2017

Thin films of europium-doped yttrium oxide ($Y_2O_3$:Eu) were prepared on Si (100) substrates by using a radio frequency (RF) magnetron sputtering. After the deposition, the films were annealed at $1000^{\circ}C$ in an air ambient for 1 hour. X-ray diffraction analysis revealed that the $Y_2O_3$:Eu films had a polycrystalline cubic ${\alpha}-Y_2O_3$ structure. The as-deposited films showed no photoluminescence (PL), which was due to poor crystalline quality of the films. The crystallinity of the $Y_2O_3$:Eu films was significantly improved by annealing. The strong red PL emission was observed from the annealed $Y_2O_3$:Eu films and the highest intensity peak was centered at around 613 nm. This emission peak originated from the $^5D_0{\rightarrow}^7F_2$ transition of the trivalent Eu ions occupying the $C_2$ sites in the cubic ${\alpha}-Y_2O_3$ lattice. The broad PL excitation band was observed at wavelengths below 280 nm, which was attributed to the charge transfer transition of the trivalent Eu ion.

• Journal of Hydrogen and New Energy
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• v.3 no.2
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• pp.9-15
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• 1992

Electroless copper plating method using an alkaline bath have been employed in copper coating of the (LM)Ni4.5Co0.1MnO.2A10.2 hydrogen storage alloy powders for electrode preparation. The plating were conducted without any pretreatment of alloy powders. For the preparation of the electrodes, about 0.12g of the copper coated alloy powder (copper to alloy ratio 1/3 by weight) was compacted with pressure of 6 tons/cm2 at room temperature. The disk-type compacts had a diameter of 10mm and thickness of about 0.24mm. The electrode characteristics were examined through SEM observations and electrochemical measurements in a half cell. The electrochemical measurement showed that the maximum discharge capacity of the electrodes prepared by using alkaline bath were 245mAh per gram of coated alloy (327mAh per gram of alloy) and appeared a considerable degradation with increasing number of cycles. The decrease of the discharge capacity after 100 cycles was about 30% It can be suggested that, with a slight of improvement, this electroless copper plating method could be applied to the preparation of the rare earth-nickel based alloy electrode.

• Progress in Superconductivity and Cryogenics
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• v.14 no.4
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• pp.5-11
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• 2012

In this review article, we focus on various co-evaporation technologies developed for the fabrication of high performance $REBa_2Cu_3O_{7-{\delta}}$ (RE: Y and Rare earth elements, REBCO) superconducting films. Compared with other manufacturing technologies for REBCO films such as sputtering, pulsed laser deposition (PLD), metal-organic deposition (MOD), and metal organic chemical vapor deposition (MOCVD), the co-evaporation method has a strong advantage of higher deposition rate because metal sources can be used as precursor materials. After the first attempt to produce REBCO films by the co-evaporation method in 1987, various co-evaporation technologies for high performance REBCO films have been developed during last several decades. The key points of each co-evaporation technology are reviewed in this article, which enables us to have a good insight into a new high throughput process, called as a Reactive Co-Evaporation by Deposition and Reaction (RCE-DR).

• Economic and Environmental Geology
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• v.25 no.4
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• pp.463-477
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• 1992

The study area consists of sedimentary and volcanic rocks of Gyeongsang Supergroup, granitoid intrusives, and hornfelses around the granitoids. Granitoid intrusives occur in small stocks in Nijeon-ri, Uggogri, and Yul-ri area. The masses in Nijeon-ri and Uggog-ri are hornblende-biotite granodiorite, biotite granodiorite respectively, and Yul-ri mass is biotite granite. Surrounding sediments of these masses were thermally metamorphosed and contact aureoles were formed. The studied granitoids are considered to be formed by sequential crystallization-differentiation from calc-alkalic granitoid magma. Metamorphic minerals occurring in contact aureole are chlorite, actinolite, epidote, and biotite. Diopside and hornblende are observed in small amount in some lithology around contact aureole. The lithology of contact aureole is predominantly silty and sandy, and characteristic metamorphic minerals were poorly developed because of low temperature metamorphism. Low temperature in contact aureole could be deduced from the facts that the intrusions were small size, shallow depth, low temperature, and rare movement of volatiles from magma.

• Journal of Korea Foundry Society
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• v.20 no.1
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• pp.29-37
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• 2000

The purpose of this study is to investigate the effect of misch metal addition on the microstructure and mechanical property of rapidly solidified AZ91 alloy by melt spinning process. As the contents of misch metal(rare earth element:Ce,La, Nd, Pr)was increased, the microstructure of RS ribbons and extrudates became finer than those of AZ91, and RE related phases($Al_{11}RE_3$, $Al_2RE$) were formed. At room temperature, the rapidly solidified AZ91+1 wt%Mm alloy showed the highest tensile strength, 430 MPa due to precipitation strengthening of${\beta}(Mg_{17}Al_{12})$ phase and Al11RE3 phase. At the elevated temperature, the mechanical property of AZ01+3 wt%Mm alloy was higher than those of other Mg alloys. The reasons were that $Al_{11}La_3$ phase was thermally stable and suppressed the grain growth. In contrast with $Al_{11}La_3$ phase, ${\beta}$ phase was thermally unstable and could not suppress the grain growth at the elevated temperature. Therefore, Al11RE3 phase contributed to improve the thermal stability of RS AZ91 Alloy.

• Journal of the Korean Magnetic Resonance Society
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• v.10 no.2
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• pp.197-202
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• 2006

[ $^{11}B$ ] nuclear magnetic resonance (NMR) measurements were performed on the single crystals of $TbB_4$ to investigate local electronic structure and 4f spin dynamics. $^{11}B$ NMR spectrum, Knight shift, spin-lattice and spin-spin relaxation rates were measured down to 4K at 8T. $^{11}B$ NMR shift and linewidth are huge and strongly temperature dependent due to the 4f moments. In addition, both are proportional to magnetic susceptibility, indicating that the hyperfine field at the boron site originates from the 4f spins of Tb. Below $T_N$, the single broad resonance peak of $^{11}B$ NMR splits into several peaks reflecting the local magnetic fields due to antiferromagnetic spin arrangements. The longitudinal and the transverse relaxation rates, $1/T_1\;and\;1/T_2$, independent of temperature above $T_N$, decreases tremendously confirming huge suppression of spin fluctuation below $T_N$.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2006.05a
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• pp.105-109
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• 2006

본 연구는 Karr column을 이용하여 희토류 염화물 수용액상에서 비희토성분인 철의 분리에 대한 기초 연구로서, 아민계 추출제인 Alamine336을 이용하여 염화물 수용액상에서 유기상의 농도, 염소이온 농도, 염산 농도에 따른 철 성분의 분리특성을 파악 하였다. Batch 실험결과 추출제 농도가 증가함에 따라 철성분 제거율이 급격히 상승하였으며, 염산 및 염소이온 농도의 경우도 유사한 결과를 나타내었다. Batch 실험을통해 확인된 불순물(Fe)을 추출하기위한 최적 조건은 염산농도 2M, 추출제 농도 0.1M, 상비 1, 추출시간 30분으로서, 이때 희토류 염화물 수용액상의 철 성분 함량은 0.7ppm 이하로서 제거율은 99.9%였다. 또한 최적의 batch 실험조건에서 반응시간(=체류시간)을 변화시키며 실험한 결과, 반응시간 60분의 조건에서 batch 실험과 유사한 결과를 얻을 수 있었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.481-482
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• 2006

플라즈마 화상표시기 (PDP)의 보호막 물질로 사용 중인 다결정 MgO의 특성을 개선하기 위하여 본 연구에서는 MgO에 희토류계 원소를 치환하여 제조하였으며, 치환량에 따른 MgO 보호막의 광학적 특성과 전기적 특성을 고찰하였다. MgO + 100 ppm $Gd_2O_3$조성으로 제작한 MgO 박막의 이차전자 방출계수 값이 순수 MgO 보다 35% 높게 나타났다. $Gd_2O_3$ dopant가 100 ppm 첨가시까지 밀도가 증가하였으나, 그 이상 첨가시 감소하는 경향을 나타냈다. 가속전압 200 V에서 이차전자 방출계수는 0.138 이었고 표면거칠기는 5.77 nm 이었으며 투과율은 550 nm 에서 95.76% 이었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.483-484
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• 2006

$Eu^{3+}$와 $Pr^{3+}$이 첨가된 $SrTiO_3$형광체를 고상반응법으로 제조하였다. $SrTiO_3:Pr$형광체는 $^3P_J(J=0,1,2){\rightarrow}^3H_4$에 의한 490nm 부근의 녹색발광과 $^1D_2{\rightarrow}^3H_4$에 의한 618nm 의 적색발광이 동시에 나타났다. $SrTiO_3:Eu$형광체는 $SrTiO_3:Pr$형광체와 달리 $^5D_0{\rightarrow}^7F_1$에 의한 583nm와 $^5D_0{\rightarrow}^7F_2$에 의한 610nm의 적색발광만 각각 관찰되었다. $SrTiO_3$의 모체에서 $Eu^{3+}$는 inversion sysmmetry를 가짐으로써 610nm의 electric dipole transition 보다는 583nm의 magnetic dipole transition이 강하게 일어났다.

• Journal of radiological science and technology
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• v.11 no.2
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• pp.21-26
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• 1988

Newly developed orthochromatic film HR series have many different types according to high speed, high resolution and special latitude. And now authors have practiced various screen-film combinations, those were usual regular type Fuji new RX film-LT screen and orthochromatic type HR films-rare earth G3, G4 screens. As a result of the experiment, we obtained high speed with high resolution and expansion of diagnostic range on the following combinations compared with usual new RX/LT series. Those combinations were RXO-G and HR-L films to skull, HR-G films to knee joint and hand part, HR-L film to abdomen. Therefore it may be desirable to select adquate kinds of HR series films according to investigated parts.