• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.2
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• pp.352-354
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• 2010

The effects of Au addition on the structure and the superconducting properties of Bi system bulk have been investigated. Au exists in the metalic form in above materials. It does not affect the formation and structure of the BiSrCaCuO(2223) phase. The superconducting transition temperature Tc does not change for $Bi_{1.7}Pb_{0.3}Sr_2Ca_2Cu_3O$ composite However Au doping can make the grains smaller. Metallic Au can make gathers on the grains boundary and lead to the increment of critical transport current density. The current density of $Bi_{1.7}Pb_{0.3}Sr_2Ca_2Cu_3Au_{0.5}O$ was 1000A/$cm^2$ at liquid nitrogen temperature.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.1
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• pp.89-94
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• 2007

High duality BiSrCaCuO thin films fabricated by using the i-beam sputtering method at various substrate temperatures, $T_{sub}$ and oxidation gas pressures, $pO_3$. The correlation diagrams of the BiSrCaCuO phases with Tsub and $pO_3$ are established in the 2212 and 2223 compositional films. In spite of 2212 compositional sputtering, Bi2201 and Bi2223 as well as Bi2212 phases come out as stable phases depending on $T_{sub}$ and $pO_3$. From these results, the thermodynamic evaluation of ${\Delta}H$ and${\Delta}S$, which are related with Gibbs' free energy change for single Bi2212 or Bi2223 phase, was performed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.333-336
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• 1999

The relationship between the DC degradation characteristics of the $ZnO-Bi_2O_3$ varistor and post-annealing is investigated in this study. $ZnO-Bi_2O_3$ varistors containing $SiO_2$ range 0.3 mol% were fabricated by standard ceramic techniques. The post- annealing is performed at $550^{\circ}C$ for 0, 1.5 and 5h. A little phase transition is found according to the analysis of X-ray diffraction. DC degradation tests were conducted at $115\pm3^{\circ}C$ for periods up to 22h. Current-voltage analysis was used to determine nonlinear coefficients($\alpha$). Capacitance-voltage analysis enable the donor density($N_d$) and the barrier height($E_B$) to be determined. From above analysis, it is found that the past-annealing for 5h improved degradation characteristics in $ZnO-Bi_2O_3$ with Si additive.

• Bulletin of the Korean Chemical Society
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• v.15 no.2
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• pp.115-118
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• 1994

Samples of ($Bi_{2-x}Sb_x)PbSr_2Ca_2Cu_3O_y$, compositions with x=0.0, 0.1, and 0.2 were prepared by solid-state reaction. The solubility of Sb into the 2223 phase is lower than 0.05 for the ratio of Sb/Bi. The lack of stability of the Sb-substituted $Bi_2O_2$ double layers is likely to cause the solubility low. There is no great dependence of lattice parameters on the Sb-content, and bonds around the square-pyramidal Cu atom are not affected by the $Sb^{3+}$ ion substituted. The superconducting transition temperature of this system is decreased gradually with increase of Sb, which is tentatively attributable to the perturbation of the Bi 6p-O 2p band and/or to the low volume fraction of the 2223 phase.

• Bulletin of the Korean Chemical Society
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• v.34 no.7
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• pp.2167-2170
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• 2013

A low-cost and simple recycling process of waste thermoelectric modules has been investigated using chemical reduction methods. The recycling is separated by two processes, such as dissolving and reduction. When the waste thermoelectric chips are immersed into a high concentration of $HNO_3$ aqueous solution at $100^{\circ}C$, oxide powders, e.g., $TeO_2$ and $Sb_2O_3$, are precipitated in the $Bi^{3+}$ and $HTeO{_2}^+$ ions contained solution. By employing a reduction process with the ions contained solutions, $Bi_2Te_3$ nanoparticles are successfully synthesized. Due to high reduction potential of $HTeO{_2}^+$ to Te, Te elements are initially formed and subsequently $Bi_2Te_3$ nanoparticles are formed. The average particle size of $Bi_2Te_3$ was calculated to be 25 nm with homogeneous size distribution. On the other hand, when the precipitated powders reduced by hydrazine, $Sb_2O_3$ and Te nanoparticles are synthesized because of higher reduction potentials of $TeO_2$ to Te. After the washing step, the $Sb_2O_3$ are clearly removed, results in Te nanoparticles.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.296-299
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• 1999

Bi$_2Sr_2CaCu_2O$(Bi-2212) thick films were fabricated on Y2l1 substrate by screen printing method. And the samples were annealed in various atmospheres, respectively. Though samples had many voids, the sample annealed in N$_2$ ; O$_2$ = 1:0 atmosphere and the sample in N$_2$ : O$_2$ = 0:1 showed some Bi 2212 low phase in comparison to other samples. The thickness of Bi-2212 on Y2ll substrates was about 20 ${\mu}$m.

• Korean Journal of Crystallography
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• v.2 no.2
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• pp.32-40
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• 1991

The effects of compositional variation, rotation speel and pulling rate on the growth of optical quality Bi120e02(1 crystals were examined. It was found to flatten the shape of crystal-melt interface for yowing a single crystals less than about 30mm in diameter at the rotation speed of 50rpm. Diameter of crystals with flat interface was increased as the pulling rate. The precipitation of Bi40e3012 phase set limits to pulling rate of BGO crystals. Precipitate-free BGO crystals were grown under pulling rate of 2mm l hr which released the stress resulted from too hi어 Pulling rate, and from 6. IBi203·GeO2 batch composition obtained by addition of 0.1 mole Bi203 into Bi-deficient melts to fill up the deficiency resulted from gradual volatilization of Bi2O). The pale-yellow colored crystals had good quality in that dislocation density was less than 103pits/cm, and it also exhibited transmittance of 70% and optical activity of 23°/mm. and SAW velosity was measured 1700m/sec on 111 cut 110 propagating BGO crystals. The SAW filter with electrode thickness of 9.8um was fabricated by using the electron beam and dry etching technique, it makes Bi12GeO20 devices intersting for color TV IF with half device size.

• Journal of the Korean Ceramic Society
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• v.55 no.5
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• pp.461-472
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• 2018

$Gd_2O_3:Eu/Bi$ nanoparticles were synthesized via spray pyrolysis and applied for the preparation of a luminescent pearl pigment as an anti-counterfeiting material. The luminescence properties were optimized by changing the $Eu^{3+}$ and $Bi^{3+}$ concentration. Ethylene glycol was used as an organic additive to prepare the $Gd_2O_3:Eu/Bi$ nanoparticles. The highest emission intensity was achieved when the total dopant content was 10.0 at.% and the mole fraction of Bi was 0.1. The concentration quenching was mainly due to dipole-dipole interactions between the same activators, and the critical distances were 9.0 and $19.6{\AA}$ for $Eu^{3+}$ and $Bi^{3+}$, respectively. The prepared $Gd_2O_3:Eu/Bi$ powder exhibited an average size of approximately 82.5 nm and a narrow size distribution. Finally, the $Gd_2O_3:Eu/Bi$ nanophosphor coated on the surface of the pearl pigment was confirmed to have good red emission under irradiation from a portable ultraviolet light-emitting diode lamp (365 nm).

• Journal of the Korean Ceramic Society
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• v.26 no.4
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• pp.505-513
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• 1989

The sintering behavior and grain growth of ZnO in 99.0mol% ZnO-1.0mol% Bi2O3 which are the basic compositions of ZnO varistor were studied. The microstructrual observation confirmed that the final sintered density was mainly determined at the initial stage of sintering, i.e. grain rearrangement and grain growth which were induced by the penetration of eutectic melts formed at eutectic temperature(74$0^{\circ}C$). But when the liquid penetration was terminated, the grain growth did not promote further densification. Activation energy of the grain growth of ZnO in the system of 99.0mol% ZnO-1.0mol% Bi2O3 was 44.8$\pm$1.8Kcal/mol.

• Journal of Electrical Engineering and Technology
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• v.2 no.1
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• pp.98-101
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• 2007

Yttrium(Y)-substituted bismuth titanate $(Bi_{4-x},Y_x)Ti_3O_{12}$ [x=0, 0.25, 0.5, 0.75, 1](BYT) thin films were deposited using an RF sputtering method on the $Pt/TiO_2/SiO_2/Si$ substrates. The structural properties and electrical properties of yttrium-substituted $(Bi_4-xYx)Ti_3O_{12}$ thin films were analyzed. The remanent polarization of $(Bi_4-xYx)Ti_3O_{12}$ films increased with increasing Y-content. The $(Bi_{3.25}Y_{0.75})Ti_3O_{12}$ films fabricated using a top Au electrode showed saturated polarization-electric field(P-E) switching curves with a remanent polarization(Pr) of $8{\mu}C/cm^2$ and coercive field (Ec) of 53 kV/cm at an applied voltage of 7 V. The $(Bi_{3.25}Y_{0.75})Ti_3O_{12}$ films exhibited fatigue-free behavior up to $4.5{\times}10^{11}$ read/write switching cycles at a frequency of 1MHz.