• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.85-88
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• 2001

The NdBaCuO superconductor samples were Zone-melted in low oxygen partial pressure (1% O$_2$+99% Ar). The Zone-melting temperature was decreased about 120$^{\circ}C$ from 1060$^{\circ}C$ the zone-melting temperature in air. Thus the loss of liquid phase (BaCuO$_2$ and CuO) was reduced during the zone-melting process. The content of non-superconducting phase Nd422 in zone-melted NdBaCuO samples was clearly decreased, so was the substitution of Nd for Ba. The superconductivity of zone-melted Nd$\sub$1+x/Ba$\sub$2-x/Cu$_3$O$\sub$y/ prepared under low oxygen partial pressure was distinctively improved.

• Progress in Superconductivity
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• 제6권1호
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• pp.84-88
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• 2004

The polycrystalline superconductor $SmBa_2$$Cu_3$$O_{x}$ is fabricated, and intergranular magnetic properties are investigated using the critical state model, from which some useful parameters such as the critical current density and the intergranular volume fraction are obtained. The curve fitting for M-H hysteresis loop shows that the intergranular critical current density of $SmBa_2$$Cu_3$$O_{x}$ / decreases in the form of ($1-T/T_{c}$ )$^{1.5}$ . The intergranular volume fraction is influenced by granular morphology. From SEM image, the grains of $SmBa_2$$Cu_3$$O_{x}$ are found to be randomly shaped. This mean:; that the intergranular volume fraction of $SmBa_2$$Cu_3$$O_{x}$ / should be smaller than those of superconductors, of which grains are plate-shaped such as Tl-based superconductor.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1988년도 춘계학술대회 논문집
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• pp.3-6
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• 1988

Electrical and magnetic properties of $Y_1Ba_2Cu_3O_7-y$ sintered with $Bi_2O_3$ have been investigated by levitation experiment and the measurement of electrical resistivity. The effects of $Bi_2O_3$ addition on the microstructure of the sintered specimens were also investigated. The electrical resistivity in the normal state is smaller in $Y_{0.85}Bi_{0.15}Ba_2Cu_3O_{7-y}$, where the Bi is substituted into Y site, than in the basic compound $Y_1Ba_2Cu_3O_{7-y}$ due to improved microstructure. On the other hand, the microstructure is poor and electrical resistivity is larger in the $Y_1Ba_2Cu_3O_{7-y}$ sintered with excess $Bi_2O_3$. It appears that the impurity in grain boundary affect the electrical properties significantly but has little effect on the magnetic property.

• Bulletin of the Korean Chemical Society
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• 제10권1호
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• pp.5-8
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• 1989

Conventional ceramic method has been used to prepare the green phase, $Y_2BaCuO_5$, commonly observed in 90-K superconductor $YBa_2Cu_3O_P{7-{\delta}}$as an impurity phase. The powder X-ray diffraction analysis indicates that $Y_2BaCuO_5$ has an orthorhombic symmetry with lattice parameter of a = 12.2 $\AA$, b = 5.61 $\AA$, and c = 7.14 $\AA.$ The average g-value 2.13 observed in ESR spectrum is attributable to Cu2+ stabilized in $C_{4v}$ field. From the magnetic susceptibility ($\mu$eff = 2.29 BM) and the ESR measurements, it is confirmed that Cu(II) $3d^9$ electrons in $Y_2BaCuO_5$ are localized and can be characterized by Curie-Weiss behavior. Optical reflectance spectrum shows a broad absorption peak around 680 nm due to dxy ${\rightarrow}$ $dx^2-y^2$ eletronic transition.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1994년도 추계학술대회 논문집
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• pp.90-96
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• 1994

In this paper, an experiment about the fabrication method of superconductor was made in order to obtain crystal structure by making High T$\sub$C/, superconductor Y$_1$Ba$_2$Cu$_3$O$\sub$x/ to Y$_2$Ba$_1$Cu$_1$O$\sub$x/ of nonsuperconductor phase was added. 211 phase, which can approach crystal structure and growth-orientatoun, was used as seed in the 123 phase which shows the properties of superconductor. Therefore crystal growth effect was able to be attained. And the effect is expected to eleminate thin crack in the growth-process and to improve electrical properties by adding Ag to High T$\sub$c/ superconductor Y$_1$Ba$_2$Cu$_3$O$\sub$x/ combined with Y$_2$Ba$_1$Cu$_1$O$\sub$x/ .

• 마이크로전자및패키징학회지
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• 제3권1호
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• pp.25-32
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• 1996

본 연구에서는 BaTiO3에 Sr과 Pb를 치환시켜TiO3 조성의 세라믹 유전체를 제조한 후 페로브스카이트형 Ba(Cu, Mo)O3를 저융점 flux 로 첨가하여 120$0^{\circ}C$ 이하의 여러온도에 서 소결을 행하였으며 flux 첨가량의 변화에 따른 소결거동 및 유전 특성의변화를 조사하였 다. 이러한 저온 소결용 유전체 세라믹스가 MLCC의 응용시 Pt-Pd계의합금을 내부전극으로 사용가능성을 검토하였다. Flux를 4mol%첨가한 TiO3-0.04Ba(Cu,Mo)O3 조성의 유전체는 120$0^{\circ}C$의 온도에서 2시간 소결했을 경우 소결밀도는 이론밀도의 95% 에 근접하였으며 이때 의 비유전율은 8000이상을 나타내었다. 이러한 소결 온도의 감소는 저융점인 ba(Cu,Mo)O3 계의 flux가 첨가되면서 비교적 낮은 온도에서 액상을 형성하여 소결을 촉진시켰기 때문으 로 사료된다.

• 한국세라믹학회지
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• 제44권8호
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• pp.457-463
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• 2007

Y, Ba and Cu nitrates were precipitated by oxalic acid at pH 4. The Y, Ba and Cu oxalate powders were vacuum dried and characterized by XRD, DT/TGA and etc. Yttrium nitrate precipitated as $NH_4Y(C_2O_4){_2}H_2O$ and converted to $Y_2O_3$ above $450^{\circ}C$. Ba precipitated with two phases, $Ba(HC_2O_4){_2}2H_2O\;and\;Ba(C_2O_4)$. The amount of each precipitates was 4 : 1, Cu precipitated non-hydrated form, $Cu(C_2O_4)$. The vacuum drying was successful to characterize precipitated powder, which had been generally known as amorphous gel.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 춘계학술대회 논문집
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• pp.54-56
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• 2005

Fabrication of c-axis oriented $(Hg_{0.75}Rc_{0.25})Ba_2Ca_2Cu_3O_y$ thick fabricated has been attempted using Ni substrates with the buffer layer of Cr or NiO. Coexistence of $(Hg_{0.75}Rc_{0.25})Ba_2Ca_3Cu_4O_y$ pellets wad found to stabilize $(Hg_{0.75}Rc_{0.25})Ba_2Ca_2Cu_3O_y$ phase of the tape. The c-axis oriented tapes were reproducibly obtained on the NiO/Ni substerate and they recorded high $B_{irr}$ at 77K.$(Hg_{0.75}Rc_{0.25})Ba_2Ca_2Cu_3O_y$ 1223.

• 한국초전도ㆍ저온공학회논문지
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• 제14권4호
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• pp.28-31
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• 2012

We report the solid-liquid phase equilibria on the $GdBa_2Cu_3O_{7-{\delta}}$ (GdBCO) stability phase diagram in low oxygen pressures ($PO_2$) ranging from 1 to 100 mTorr. On the basis of the GdBCO stability phase diagram experimentally determined in low oxygen pressures, the isothermal sections of three different phase fields on log $PO_2$ vs. 1/T diagram were schematically constructed within the $Gd_2O_3-Ba_2CuO_y-Cu_2O$ ternary system, and the solid-liquid phase equilibria in each phase field were described. The invariant points on the phase boundaries include the following three reactions; a pseudobinary peritectic reaction of $GdBCO{\leftrightarrow}Gd_2O_3$ + liquid ($L_1$), a ternary peritectic reaction of $GdBCO{\leftrightarrow}Gd_2O_3+GdBa_6Cu_3O_y$ + liquid ($L_2$), and a monotectic reaction of $L_1{\leftrightarrow}GdBa_6Cu_3O_y+L_2$. A conspicuous feature of the solid-liquid phase equilibria in low $PO_2$ regime (1 - 100 mTorr) is that the GdBCO phase is decomposed into $Gd_2O_3+L_1$ or $Gd_2O_3+GdBa_6Cu_3O_y+L_2$ rather than $Gd_2BaCuO_5+L$ well-known in high $PO_2$ like air.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 초전도 자성체
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• pp.14-16
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• 2002

Melting and re-solidification nature of $SmBa_2Cu_3O_{7-y}$ (Sm123) grains in Ba-Cu-O (Ba:Cu=3:5) liquid containing 0.7 at.% yttrium were investigated at the temperature lower than its melt point. When Sm123 grains/liquid powder compacts were heated to a temperature between two melting points of Ba-Cu-O liquid ($1000^{\circ}C$) and a Sm123 phase ($1060^{\circ}C$) and held at this temperature for appropriate time, Sm123 grains melted partly in the liquid that was formed by melting of the liquid-forming powder. During subsequent slow cooling, (Sm,Y)$Ba_2Cu_3O_{7-y}$ solidified at the outer parts of the unmelted Sm12 grains, which is distinguished from the core regions by lower $Sm_2BaCuO_5$ (211) density.