• 한국전기전자재료학회논문지
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• 제12권1호
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• pp.44-49
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• 1999

In this study, microstructure and electrical conductivity of {(G $d_2$ $O_3$)$_{0.75}$( $Y_2$ $O_3$)$_{0.25}$}$_{x}$ (Ce $O_2$)$_{1-x}$ (0.01$\leq$x$\leq$0.25) was investigated as a function of composition x. GYO addition(x) increased the bulk density and G $d_2$ $O_3$ was found to be monoclinic at x>0.15. From the change of the lattice parameter with the addition(x), GYO solution limit for ceria was exceeded in the range of x=0.05 to 0.09. Thermal expansion coefficient(15~17$\times$10$^{-6}$ $^{\circ}C$) of GYC samples at x=0.01 to 0.07 was higher in value than that of 8YSZ(10.8$\times$10$^{-6}$ $^{\circ}C$). The electrical conductivity of GYC samples at x=0.05 showed the maximum(0.01S/cm) in value at 1073K which was 2 times higher than that of 8YSZ. The activation energy for the electrical conduction was determined to be 0.60eV in the temperature range of 1073K.3K..3K.

• Progress in Superconductivity
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• 제12권2호
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• pp.110-113
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• 2011

We have grown a Nb/Gd bilayer on a$SiO_2$/Si substrate by using a DC magnetron sputtering system, which was fabricated in situ with silicon stencil masks. In order to investigate proximity effect of the Nb/Gd bilayer, we used a planar tunnel junction with an AlOx tunnel barrier by oxidizing the Al ground electrode at the bottom. A $Co_{60}Fe_{40}$ backing of Al was deposited so as to reduce the superconductivity of the Al, ensuring a normal counterelectrode. With a 50-nm-thick Nb layer, we have measured dI/dV (dynamic conductance) by varying the thickness of Gd, which can reveal the density of states (DOS) of the Nb/Gd bilayer as a function of the Gd thickness resulting from the proximity effect of a superconductor/ferromagnet bilayer (S/F). The SF proximity effect in Nb/Gd will be discussed in comparison to our previous results of the CoFe/Nb, Ni/Nb and CuNi/Nb proximity effect; Gd is expected to show different effects since Gd has f-electrons, while CoFe, Ni, and CuNi have only d-electrons. Our studies will focus on the triplet correlation in a superconducting pair.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 1999년도 추계학술발표회 초록집
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• pp.68-69
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• 1999

• 한국결정성장학회지
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• 제9권4호
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• pp.432-436
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• 1999

Fiber growth of $Al_{2}O_{3}/R-Al-O$ (R = Y, Gd, Dy, Ho, Er) eutectic by the micro-pulling down method is described. The thermal stability and strength at elevated temperature of each materials is evaluated in relation to the microstructure.

• 한국광학회:학술대회논문집
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• 한국광학회 2003년도 하계학술발표회
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• pp.284-285
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• 2003

Significant research interest in the growth and characterization of $Y_2$O$_3$：Eu$^{3+}$ thin films has been shown over the last few years because of the promise for applications of display devices. Although an Eu-doped oxysulfide (Eu： $Y_2$O$_2$S) which has an efficiency of 13％ has been used for a traditional cathode ray tube (CRT) red phosphor, the sulfide system is known to degrade rapidly under the high current densities needed for field-emission display (FED) technology. (omitted)d)

• 한국자기학회지
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• 제1권2호
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• pp.55-59
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• 1991

희토류-3d 천이원소인 비정질${[{(Fe_{80}CO_{20})}_{0.98}RE_{0.02}]}_{80}B_{20}(RE=Nd,\;Sm,\;Gd,\;Tb)$ 합금 리본시료에 대한 자기적 성질을 조사하기 위하여 시료진동형 자력계(vibrating sample magnetometor)를 이용하여 77 K부터 900 K까지의 온도 영역에서 포화자화 값을 온도의 함수로 측정 한후, Curie 온도 ($T_{c}$)와 Bloch 상수등을 추정하였다. 이들로 부터 spin wave stiffness 상수, 교환상호작용(exchange interaction)의 범위와 평균자승거리($$)등을 계산하였으며 각 희토류 원소에 대한 치환효과를 비교 분석하였다.

• Transactions on Electrical and Electronic Materials
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• 제15권2호
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• pp.69-72
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• 2014

White LEDs, based on blue LED chips coated with a yellow emitting phosphor (YAG:Ce), have several disadvantages. In this paper, we report the improvement in CRI [Color Rendition Index] using $GdAl_5O_{12}:Ce$ (GdAG:Ce) and related phosphors for blue LEDs. A modified combustion synthesis route using mixed fuel was used for synthesis route. By using this procedure, we formed the desired compounds in a single step. LEDs were then fabricated by coating the blue LED chips (CREE 470 nm, 300 micron) with the GdAG:Ce phosphor dispersed in epoxy resin. The CRI typically between 65~70 for the YAG:Ce based LED was improved to 87 for LEDs fabricated from the Gd(Al,Ga)G phosphors.

• 자원환경지질
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• 제38권2호
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• pp.187-196
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• 2005

석류석 구조에서, 양이온이 점할 수 있는 구조적 위치는 사면체, 팔면체 및 이들과 능을 공유하고 있는 배위다면체의 중심 등이다. 이들 중, 사면체의 자리를 차지하는 양이온의 크기는 석류석의 단위포의 크기와 밀접한 관계를 가진다. 따라서 4-배위 자리에 비교적 이온반경이 큰 철을 함유하고 있는 석류석은 방사성 폐기물 내에 함유된 비교적 이온반경이 큰 악티나이드 원소를 고정시키기 위한 유망한 매트릭스로써 고려될 수 있다. 따라서 본 연구에서는 $Ca_{1.5}GdCe_{0.5}ZrFeFe_3O_{12}$인 조성을 가진 석류석을 합성하여 이들의 상평형 관계 및 특성을 연구하였다. 혼합된 시료는 $200{\~}400{\cal}kg/{\cal}cm^2$의 압력으로 성형한 후, $1100{\~}1400^{\circ}C$ 범위에서 온도 및 분위기를 변화시키면서 소결하였으며, 합성된 시료는 XRD 및 SEM/EDS를 사용하여 상분석과 정량분석을 실시하였다. 실험결과, 석류석은 소결온도 $1300^{\circ}C$에서 최적의 합성상을 얻을 수 있었지만, 미량의 페로브스카이트 및 미지의 상이 공존하였다. 석류석과 페로브스카이트의 화학조성은 각각 $[Ca_{l.2-1.8}Gd_{0.9-1.4}Ce_{0.3-0.5}]^{VIII}[Zr_{0.8-1.3}Fe_{0.7-1.2}]^{VI}[Fe_{2.9-3.1}]^{IV}O_{12}$ 및 $Ca_{0.1-0.5}Gd_{0.0-0.8}Ce_{0.1-0.5}\;Zr_{0.0-0.2}Fe_{0.9-1.1}O_3$ 이었다. 특히 화학양론적 조성과 비교 시, 합성된 석류석의 8-배위 자리를 점하고 있는 Ca의 초과 및 Ce의 결핍된 양상을 보였다. 이는 6-배위 자리에서의 Zr 및 Fe의 화학조성과 밀접한 관계를 지닌다.

• Journal of Magnetics
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• 제16권4호
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• pp.337-341
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• 2011

The magnetic and magnetocaloric properties of $Gd_{1-x}Ce_xAl_2$ (x = 0, 0.25, 0.5, 0.75) intermetallic compounds alloys have been investigated in detail for the first time. XRD patterns indicated that all the samples were crystallized in a single phase with $MgCu_2$-type structure (Laves phase). Ce substitution for Gd increased the lattice parameters and decreased the Curie temperature from 163 K for x = 0 to 37 K for x = 0.75. A maximum entropy change of 3.82 J/kg K was observed when a 2 T magnetic field was applied to the x = 0 sample. This entropy change decreased with increasing Ce content to 2.04 J/kg K for the x = 0.75 sample.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.116-119
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• 2002

A different route to the synthesis of $Eu^{3+}$ - activated matrices such as $YAlO_{3}$ and $GdAlO_{3}$ and luminiscent properties of these compounds, were studied. The new route (Combustion method) consist of the redox reactions between the respective metal nitrates and urea in a preheated furnace at ${500^{\circ}C}$. The Phosphor thus obtained were then heated at ${1000^{\circ}C}$ for 2-3 hours to get better luminiscent properties. The incorporation of $Eu^{3+}$ activator in these phosphors were checked by luminiscence investigations. Scanning electron microscopy (SEM) studies were carried out to understand surface morphological features and the particle size. X-ray energy dispersive analysis (EDAX) was also performed for the qualitative analysis of the phosphors.