• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1137-1139
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• 1993

The superconducting thin films of $YBa_2Cu_3O_{7-x}$ were deposited on (100) sapphire substrates at low temperature by rf magnetron sputtering and annealed at $895^{\circ}C$ for 60 sec. using rapid-thermal-annealing(RTA) technique. The films were characterized by SEM, four-point probe resistivity measurement, XRD, and AES. The RTA processed HTS films had a preferential structure with c-axis normal to the substrate surface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.349-352
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• 2004

The improvement of critical temperature $(T_c)$, critical magnetic field $(H_c)$, and critical current density $(J_c)$ of superconductor is important for practical applications. In this study, the additives such as metal oxides were used to improve the preparation conditions of $YBa_2Cu_3O_x$ superconducting bulk samples and depending on additives the properties of $YBa_2Cu_3O_x$ superconductor were studied. The effects of additives to the density, grain alignment, and porosity of samples that affect the critical current density of superconductor also have been investigated.

• Bulletin of the Korean Chemical Society
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• v.11 no.5
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• pp.379-383
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• 1990

$YBa_2Cu_{3-x}Ni_xO_{7-{\delta}}$, with x = 0.05, 0.2, 0.4, 0.7 and 1.0 had been prepared by the thermal decomposition of corresponding nitrates. Among them, the sample with x = 0.05 shows above-liquid-$N_2$ temperature superconductivity with $T_c$ of 88.7K. According to the X-ray diffraction analysis, its crystal symmetry was estimated as orthorhombic with the lattice parameters of a = 3.866${\AA}$, b = 3.893${\AA}$, c = 11.715${\AA}$. The chemical composition of the sample was determined by electron probe microanalysis and the chemical composition around its grain boundaries was carefully studied by the X-ray line scanning technique. From the observed binding energy of Ni-$2p_{3/2}$ orbital electron (B.E. = 853 eV) measured by X-ray photoelectron spectroscopy, the valency state of nickel stabilized in $YBa_2Cu_{2.95}Ni_{0.05}O_{7-{\delta}}$ oxide lattice could be determined to be Ni(II).

• Progress in Superconductivity and Cryogenics
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• v.10 no.1
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• pp.1-5
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• 2008

The effect of $BaCeO_3$ doping on the critical current density of YBCO film by TFA-MOD method was studied. $BaCeO_3$ doping was made by two method; one is direct addition of $BaCeO_3$ nano-sized powder prepared by citrate process followed by grinding with planetary ball mill for 10 hours. Another is addition of Ba-Ce precursor solution prepared with Ba-acetate and Ce acetate dissolved in TFA to the YBCO-TFA precursor solution. The film was made by standard dip coating and heat treatment process with conversion temperature of $790^{\circ}C$ in 1000 ppm oxygen containing moisturized Ar gas atmosphere. The direct addition of $BaCeO_3$ powder resulted in YBCO film with good epitaxial growth and no evidence of second phase formation. The addition through precursor solution resulted in the increase of critical current density upto 30 at% doping and uniform dispersion of $BaCeO_3$ fine inclusion was confirmed by SEM-EDX.

• Transactions on Electrical and Electronic Materials
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• v.5 no.3
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• pp.120-121
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• 2004

YBaCuO thick films were fabricated by plasma enhanced chemical vapor deposition, and the crystallinity and the superconducting properties were investigated. The growth temperature to obtain the thick films was decreased by around 150$^{\circ}C$ due to plasma enhancement. The zero resistivity temperatures for films grown at 590$^{\circ}C$ and 620$^{\circ}C$ were 55 and 80 K, respectively.

• 한국초전도학회:학술대회논문집
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• v.12
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• pp.70-70
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• 2002

• Proceedings of the Materials Research Society of Korea Conference
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• 1996.05a
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• pp.153-153
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• 1996

• Korean Journal of Crystallography
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• v.14 no.2
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• pp.51-55
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• 2003

SrTiO₃ (STO) thin fims were deposited on the biaxially textured Ni-3 wt%W alloy substrates to be used as a single buffer layer for YBa₂CU₃O/sub 7-8/(YBCO) coated conductor. Thin films of YBCO and STO were deposited using pulsed laser. The deposition condition for epitaxial growth of STO on the textured metal was identified, and YBCO coated conductor with a single STO buffer layer with critical current density of 1.2 MA㎠ at 77 K under zero magnetic field and critical temperature of 86 K, was fabricated.

• Journal of the Korean Ceramic Society
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• v.25 no.2
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• pp.154-160
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• 1988

Almost single phase of Y1Ba2Cu3Ox, which exhibits the onset of superconducting transition at 90K, has been prepared via a conventional ceramic processing route followed by an anneal for a period of 10 hours at 45$0^{\circ}C$ in an atmosphere of 100% O2. The mean value for the oxygen content has been determined as x=6.85$\pm$0.02 by an iodometric titration technique. X-ray photoemission spectra are found to be consistent with a mixture of the d8(Cu3+) and d9(Cu2+) as the ground state and reveals that the local concentration of Cu3+ decreases with depth from the surface where x corresponds to 7.0. This is explained as being associated with the intercalation of oxygen during cooling from the annealing temperature.

• Journal of the Korean Vacuum Society
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• v.3 no.1
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• pp.117-121
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• 1994

SrTiO3(100) 단결정을 3keV 아르곤이온으로 에칭하면 표면원소의 산화 상태가 환원되고 표면의 거칠기가 증가하는 것이 XPS와 SEM으로 측정되었다. 그러나 3keV의 산소이온으로 에칭하면 표면원소 의 화학적 상태도 변하지 않고 표면도 평탄한 상태로 계속 유지된다. 산소 이온에 의하여 에칭된 SrTiO3 기판상에 off-axis rf 스퍼트링 방법으로 성장된 YBa2Cu3Ox 박막이 아르곤 이온에 의하여 에칭 된 SrTiO3 기판상에 성장된 YBa2Cu3Ox 박막보다 높은 Tc,zero and Jc를 보여주었다. 이논문은 YBCO초전 도 박막의 성장과 전자공학적 활용을 위한 리토그라피 공정에서 이온밀링 공정의 조건은 매우 주의하여 선택되어야 함을 보여준다.