• 한국재료학회지
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• 제3권4호
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• pp.410-421
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• 1993

Bi-Sr-Ca-O 초전도성계에서 $Bi_2O_3-(Sr_2CaCu_2O_x$)의 pseude binary계를 선택하여 $Sr_2CaCu_2O_x$에 $Bi_2O_3$를 5%단위로 40 cation mole% Bi까지 첨가하면서 $850^{\circ}C$ 초전도상 및 공존하는 상들의 평형 및 반응 경로들을 XRD, SEM, EDS, DTA를 이용하여 분석하였다. Bi의 함량이 35 mole% Bi보다 클 때에는 $Bi_2Sr_2CaCu_2O_8$상과 공존하는 액상이 형성되며 2212상의 액상으로 존재하며 액상의 냉각시 제일 먼저 $Bi_2Sr_2CaCu_2O_8$상 주의에 석출된 것이 관찰되었다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2000년도 추계학술대회논문집
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• pp.124-128
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• 2000

The high Tc phase disappeared and low Tc phase increased in the substitution of transistion elements for Bi ions. The high Tc phase decreased in the substitution of Si and Sn for Bi ions. The high Tc phase increased in the substitution of Sb, As and P Which Were the same group of Bi for Bi ions. The substitution of P ions was the most effective and then the high Tc phase was formed in large quantity by replacing Bi ions with 30%of P ions.

• 한국재료학회지
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• 제24권2호
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• pp.116-122
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• 2014

$Bi_2Sr_2CaCu_2O_x$(Bi-2212) and $Bi_2Sr_2Ca_2Cu_3O_y$(Bi-2223) high-Tc superconductors(HTS) have been manufactured by plasma spraying, partial melt process(PMP) and annealing treatment(AT). A Bi-2212/2223 HTS coating layer was synthesized through the peritectic reaction between a 0212 oxide coating layer and 2001 oxide coating layer by the PMP-AT process. The 2212 HTS layer consists of whiskers grown in the diffusion direction. The Bi-2223 phase and secondary phase in the Bi-2212 layer were observed. The secondary phase was distributed uniformly over the whole layer. As annealing time goes on, the Bi-2212 phase decreases with mis-orientation and irregular shape, but the Bi-2223 phase increases because a new Bi-2223 phase is formed inside the pre-existing Bi-2212 crystals, and because of the nucleation of a Bi-2223 phase at the edge of Bi-2212 crystals by diffusion of Ca and Cu-O bilayers. In this study the spray coated layer showed superconducting transitions with an onset Tc of about both 115 K, and 50 K. There were two steps. Step 1 at 115 K is due to the diamagnetism of the Bi-2223 phase and step 2 at 50 K is due to the diamagnetism of the Bi-2212 phase.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 추계학술발표대회 개요집
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• pp.262-264
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• 2005

$Bi_{2}Sr_{2}CaCu_{2}O_{x}$(Bi-2212) and $Bi_{2}Sr_{2}Ca_{2}Cu_{3}O_{y}$(Bi-2223) high-$T_{c}$ superconductor(HTS) coating have been prepared by plasma spraying and heaat treatment. The Bi-2212 HTS coating later is synthesized through the peritectic reaction between Sr-Ca-Cu oxide coating layer and Bi-Cu oxide coating later, and $Bi_{2}Sr_{2}CaCu_{2}O_{y}$(Bi-2212) superconducting phase grow by partial melting process. The superconducting characteristic depends strongly on the conditions of the partial melting process. the Bi-2212 HTS layer consists of the whiskers grown in the diffusion direction. Above the 2212 layer, Bi-2223 phase and secondary phase was observed. The secondary phase is distributed uniformly over the whole surface. This is caused to the microcrack on the coatings surface. Despite everything, the film shows superconducting with an onset $T_{c}$ of about 115K. There are two changes steps. One changes (1step) at 115K is due to the diamagnetism of the Bi-2223 phase and the other changes (2step) at 78K is due to the diamagnetism of the Bi-2212 phase.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.65-68
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• 1999

A well oriented Bi2212 superconductor thick films were fabricated by screen printing with a Cu-free Bi-Sr-Ca-O mixture powder on a copper plate and heat-treating at 820-88$0^{\circ}C$ for several minute in air. During the heat-treatment, the printing layer partially melted by reaction between the Cu-free precursor and CuO of the oxidizing copper plate. In the partial melting state, it is believed that the solid phase is Bi-free phase and Cu-rich phase and the composition of the liquid is around Bi : Sr : Ca : Cu = 2 : 2 : 0 : 1. Following the partial melting, the Bi2212 superconducting phase is formed at Bi-free phase/liquid interface by nucleation and grows. With decreasing the Bi composition in the precursor powder, the critical temperature(T$_{c}$) of the fabricated Bi2212 thick film increased to about 79 K.K.

• 한국세라믹학회지
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• 제28권2호
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• pp.160-166
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• 1991

Microstructure and phase changes during the sintering of ZnO varistors were studied in ZnO-Bi2O3-CoO-Sb2O3 and ZnO-Bi2O3-CoO-Sb2O3-Cr2O3 systems using acanning electron microscopy (SEM) with an energy dispersive X-ray analysis (EDAX), X-ray diffraction (XRD) and differential thermal analysis (DTA). The spinel phase and the Bi2O3 phase were formed by the decomposition of the pyrochlore phase during heating. The spinel particles (2-4$\mu\textrm{m}$), which were formed both along ther grain boundaries and within the ZnO grain, were always found near the pyrochlore phase. Intergranular phases (Bi2O3 and pyrochlore) were precipitated from the liquid phase during cooling. The Bi2O3 phases were located at the triple (or multiple) point of the ZnO grains. Cr2O3 played a role in decreasing the formation temperature of the spinel phase and Bi2O3 phase during sintering, and inhibited the grain growth.

• 한국결정성장학회지
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• 제23권4호
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• pp.189-194
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• 2013

기계적 합금법을 이용하여 Mg, Sb, Bi을 planetary 볼밀에서 24~48시간 볼 밀링하여 $Mg_3Sb_2$와 $Mg_3Bi_2$ 단일 결정상의 합금분말을 얻었다. 출발조성은 $Mg_3Sb_2$상의 경우 3Mg : 1.8Sb, $Mg_3Bi_2$상은 3Mg : 1.6Bi이었다. 얻어진 두 합금 분말을 여러 비율로 혼합하여 70 MPa의 압력 하, 723 K에서 1시간 가압소결하여 $Mg_3Sb_2-Mg_3Bi_2$ 복합체를 제조하였다. 복합체의 주 결정상은 $Mg_3Bi_2$상과 유사한 안정한 상이었고 미량의 Bi상이 존재하였다. EDS 맵핑결과 가압소결체들의 조성분포는 불연속적이며 독립적으로 나타나서 $Mg_3Sb_2-Mg_3Bi_2$계 복합체가 제조되었다는 것을 확인할 수 있었다.

• 한국주조공학회지
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• 제32권2호
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• pp.91-97
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• 2012

The effects of Bi and Sb additions on the microstructures and casting properties in lead-free Cu-Zn-Sn broze were investigated. (1) When only Bi was added to the bronze, Bi was precipitated on the ${\delta}$ phase of ${\alpha}$ dendrite cell boundary. When Bi and Sb were added together, Bi was precipitated on the ${\delta}_A$ which was the Sb-rich area in the ${\delta}$ phase. (2) The addition of Sb accelerated the formation of ${\delta}$ phase, and when Sb, Bi and Pb were added, Bi and Pb were precipitated as mixed solution in the ${\delta}_A$ phase. (3) The combined addition of Sb and Bi resulted in the suppression of shrinkage due to the complementary effects of the mass feeding of ${\alpha}$-dendrite cluster covered with ${\delta}$ phase and sealing of micro-shrinkage in the ${\delta}$ phase by solidification expansion of Bi.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.571-574
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• 2003

The thin films fabricated by using the layer-by-layer sputtering was compared with the thin film fabricated by using the evaporation method. Re-evaporation in the form of Bi atoms or $Bi_2O_3$ molecules easily bring out the deficiency of Bi atoms in thin film due to the long sputtering time of the layer-by-layer deposition. On the other hand, the respective atom numbers corresponding to BiSrCaCuO phase is concurrently supplied on the film surface in the evaporation deposition process and leads to BiSrCaCuO phase formation. Also, it is cofirmed that by optimizing the deposition condition, each single phase of the Bi2201 phase and the Bi2212 phase can be fabricated, the sticking coefficient of Bi element is clearly related to the changing of substrate temperature and the formation of the Bi2212 phase.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.490-493
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• 2002

Phase intergrowth some kinds of the Bi$_2$Sr$_2$Ca$\_$n-1/Cu$\_$n/O$\_$y/ phases is observed in the thin film fabrication at ultralow co-deposition with multi targets by means of ion beam sputtering. The molar fraction of the Bi2212 phase in the mixed crystal of the grown films is investigated as a function of the applied ozone pressure and the substrate temperature. The activation energy for the phase transformation from the Bi2201 to the Bi2212 is estimated in terms of the Avrami equation. This study reveals that the formation of a liquid phase contributes significantly to the construction of the Bi2212 phase in the thin films, differing from the bulk synthesis.