• Progress in Superconductivity
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• v.4 no.2
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• pp.162-167
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• 2003

The critical current value of Bi-2223/Ag tape can be influenced by various factors. In particular, it was known that properties of precursor powders could affect the formation of Bi -2223 and grain growth rate of the same. Since, moistures and organic matters can easily contaminate the precursor powders of Bi-2223 tapes and degrade properties of superconductors, the precursor powders should be kept in optimal conditions to minimize contamination. In this study, the effect of moisture and organic matters has been investigated. A Bi-2223/Ag tape contaminated with a large amount of moisture and organic matter has been characterized by low critical current values and bubbling. It has been found that as the quantity of moisture increases, the Bi-2223 phases are formed at lower temperature and the amount of non-superconducting phase increases.

• Proceedings of the Materials Research Society of Korea Conference
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• 1996.05a
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• pp.113-113
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• 1996

• Proceedings of the Materials Research Society of Korea Conference
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• 1992.05b
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• pp.93-93
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• 1992

• Proceedings of the Materials Research Society of Korea Conference
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• 1996.11a
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• pp.168-168
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• 1996

• Proceedings of the Materials Research Society of Korea Conference
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• 1994.05a
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• pp.42-43
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• 1994

• Proceedings of the Materials Research Society of Korea Conference
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• 1994.05a
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• pp.44-45
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• 1994

• Proceedings of the Materials Research Society of Korea Conference
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• 1997.05a
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• pp.45-45
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• 1997

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.2
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• pp.66-69
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• 2009

The compositional dependence of bismuth iron oxides and effect of La-substitutions in the structure of $BiFeO_3$ compounds were investigated, which compounds were synthesized by conventional ceramic processing. It is shown that some of bismuth iron oxides including $BiFeO_3$ show the narrow single phase region. The effect of La-doping in $BiFeO_3$ was presented as disappearance of many impurity phases of Bi-Fe-O compounds. The lower electrical resistivity was obtained as those compositions of Fe deficient region and La-doped $BiFeO_3$. The saturation magnetization of La-doped $BiFeO_3$ was increased with La content. The dielectric dispersion was also observed for those Bi-Fe-O compounds with Fe deficient and La-doped $BiFeO_3$ at low frequencies under 1 kHz.

• Korean Journal of Materials Research
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• v.6 no.7
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• pp.684-691
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• 1996

To enhance the formation of Bi,Sr,Ca,Cu,O,(Bi-2223) single phase in a shorter reaction time, the intermediate compounds such as Bi,Sr,CuO,(Bi-2201). BizSr,CaCuz08(Bi-2212) and (Ca, Sr,, ,9)CuOz in the Bi-Sr-Ca-Cu-0 system were used as the precursors. The formation of Bi-2223 was enhanced in the mixture of Bi-2201 and (Ca, ,,Sr, 119)C~eOsZpe,c ially from the mixture with (Ca, 9I Sr, ,,)CuO,-rich composition compared to Bi, iPb, 4Sr2Ca,Cu3010-cxo mposition. The formation of Bi- 2223 essentially completed within 60h at 860$^{\circ}$C and 870$^{\circ}$C. However, a small amount of the remnant Bi-2212 phase did not disappear even after a prolonged reaction at 870'C. The merit of the proposed synthetic method using the intermediate precusors can be summarized as a shorter reaction time for the formation of Bi-2223 phase, in addition to a smaller amount of second phases compared to the conventional solid-state reaction method.

• Proceedings of the Materials Research Society of Korea Conference
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• 2002.05a
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• pp.53-53
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• 2002