• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 반도체 재료 센서 박막재료 전자세라믹스
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• pp.42-45
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• 2004

High quality CdTe single crystal for the solar cell fabrication was grown by vertical Bridgman method. The etch pits patterns of {111}surfaces of CdTe etched by Nakagawa solution was observed the {111} A composed of Cd atoms with typical triangle etch pits of pyramid mode. From the photoluminescence measurement on {111}A, we observed free exciton($E_x$) existing only higy quality crystal and neytral acceptor bound exciton($A^0$,X) having very strong peak intensity. Then, the full width at half maximum and binding energy of neutral acceptor bound exciton were 7 meV and 5.9 meV, respectively. By Haynes rule, an actibation energy of impurity was 59 meV. Therefore, the origins on impurity level acting as a neutral acceptor were associated Ag or Cu elements.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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• pp.171-174
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• 1999

We have characterized solid solution Y$_{l-x}Ca_xBa_2Cu_3O_y$ (0${\le}$x${\le}$0.3) materials by measuring the XRD pattern, resistivity and hole concentrations, etc. As Ca concentration increases, T$_c$, is decreased monotonically because the hole concentration on the superconducting plane increases beyond the optimum region in the electronic phase diagram due to the hole transfer from the Cu-O chain to the CuO$_2$ plane. A very small amount of secondary phase have large effects on the analysis of oxygen content and hole concentration etc. The results before the correction of impurity phase are compared with those after the correction.

• Bulletin of the Korean Chemical Society
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• 제13권6호
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• pp.663-665
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• 1992

The superconducting $YBa_2Cu_4O_8$ was synthesized in oxygen condition at 1 atm. The starting material with 1 : 2 : 4 composition was obtained by pyrolysis of EDTA complex, which was converted to 1-2-3 phase during densification, followed by the 1-2-4 phase recovery at $810^{\circ}C$ . The phase presents were identified by XRD, TG, DTA and AC magnetic susceptibility. Our data indicated that considerable amounts of 1-2-4 phase formed but with the 1 : 2 : 3 phase or possibly 2-4-7 as visible. As the P($O_2$) increased with temperature, impurity peak, CuO ($2{\Theta}$ = 38.8), gradually decrease, and we conclude that the 1-2-4 phase is predominant bulk superconductor under the high oxygen pressure.

• Journal of Electrochemical Science and Technology
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• 제3권3호
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• pp.123-134
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• 2012

The electrochemical performance of positive pole grids of lead-acid batteries made of Pb-0.08%Ca-1.1%Sn alloys without and with 0.1 wt% of each of Cu, As or Sb and with 0.1 wt% of Cu, As and Sb combined was investigated by electrochemical methods in 4.0 M $H_2SO_4$. The corrodibility of alloys under open-circuit conditions and constant current charging of the positive pole, the positive pole gassing and the self-discharge of the charged positive pole were studied. All impurities (Cu, As, Sb) were found to decrease the corrosion resistance, $R_{corr}$ after 1/2 hour corrosion, but after 24 hours an improvement in $R_{corr}$ was recorded for Sb containing alloy and the alloy with the three impurities combined. While an individual impurity was found to enhance oxygen evolution reaction, the impurities combined significantly inhibition this reaction and the related water loss problem was improved. Impedance results were found helpful in identification of the species involved in the charging/discharging and the self-discharge of the positive pole. Impurities individually or combined were found to increase the self-discharge during polarization (33-68%), where Sb containing alloy was the worst and impurities combined alloy was the least. The corrosion of the positive pole grid in the constant current charging was found to increase in the presence of impurities by 5-10%. Under open-circuit, the self-discharge of the charged positive grids was found to increase significantly (92-212%) in the presence of impurities, with Sb-containing alloy was the worst. The important result of the study is that the harmful effect of the studied impurities combined was not additive but sometimes lesser than any individual impurity.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.237-242
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• 2001

The stochiometric mix of evaporating materials for the CuGaSe$_2$ single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, CuGaSe$_2$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were 610$^{\circ}C$ and 450$^{\circ}C$, respectively The crystalline structure of single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). From the photocurrent spectrum by illumination of perpendicular light on the c-axis of the CuGaSe$_2$ single crystal thin film, we have found that the values of spin orbit splitting Δ So and the crystal field splitting ΔCr were 91 meV and 249.8 meV at 20 K, respectively. From the Photoluminescence measurement on CuGaSe$_2$ single crystal thin film, we observed free excition (Ex) existing only high quality crystal and neutral bound exiciton (D$^{\circ}$,X) having very strong peak intensity. Then, the full-width-at-half-maximum(FWHM) and binding energy 7f neutral acceptor bound excision were 8 meV and 35.2 meV, respectivity. By Haynes rule, an activation energy of impurity was 355.2 meV

• 한국초전도ㆍ저온공학회논문지
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• 제26권2호
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• pp.1-4
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• 2024

We investigated Pb_10-xCu_x(PO₄)₆ (0.9 < x < 1.1) (LK-99) and Cu₂S, presumed to be contained as an impurity in LK-99, in a wide spectral range from far infrared to ultraviolet using optical spectroscopy. The optical conductivity spectra of both samples were obtained from measured reflectance spectra at various temperatures from 80 to 434 K. Both samples showed several infrared-active phonons in the far and mid-infrared regions. LK-99 showed typical insulating features with a band gap of ~1 eV. Cu₂S showed a nonmonotonic temperature-dependent trend and two energy gaps: one energy gap of ~93 meV and a band gap of 2.42 eV. Our results indicate that LK-99 cannot be a superconductor because it is an insulator with a large band gap.

• 자원리싸이클링
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• 제25권4호
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• pp.49-53
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• 2016

주석 폐자원으로부터 회수된 주석 조금속을 메탄술폰산 전해액에서 전해정련을 수행하여 고순도 주석을 회수하고자 하였다. 전해정련층 표면형상을 관찰한 결과 주석 전해정련 시 glycol계 유기첨가제를 통해 균일하게 주석이 전착되었고, 수지상 형상 및 박리현상은 발생하지 않았다. 주석 조금속 및 전해정련층의 순도를 ICP-OES로 분석한 결과 주석 조금속은 은, 구리, 납, 니켈 등의 불순물이 함유되어 97.280 wt.%의 주석순도를 나타내었고, 전해정련을 수행 후 순도 분석결과 주석의 순도는 99.956 wt.%으로 증가하였다. 순환 전압전류 시험결과 유기첨가제는 주석 전해정련 시 불순물의 환원반응을 억제 또는 가속시키는 역할을 하는 것으로 판단된다.

• 대한화학회지
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• 제36권6호
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• pp.818-823
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• 1992

Y, Er, Yb, Ba 및 Cu를 각각 포함하는 유기금속 화합물인 2-Ethylhexanoate 화합물을 합성하였다. 합성된 유기금속화합물들은 모두 공통용매에 녹아 균일혼합물을 형성하였으며 이들을 원료물질로 하여 고온초전도체 $YBa_2Cu_3O_{7-\delta}(Y_{123})$, $ErBa_2Cu_3O_{7-\delta}(Er_{123})$ 및 $YbBa_2Cu_3O_{7-\delta}(Yb_{123})$를 제조하였다. X-선 회절분석결과 이들은 단일상이 아니었으며 $YBa_2Cu_4O_8(Y_{124})$를 포함한 약간씩의 불순물상을 포함하고 있었고, 이것은 자화율 측정에서도 확인되었다. Ceramic method로 제조한 시료에 비하여 임계온도가 대체로 높았으며, 부피반자성자화율은 큰 변화가 없는 것으로 판단된다.

• Journal of Magnetics
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• 제12권3호
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• pp.118-123
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• 2007

We have studied the effect of Au-Cu back layer system ${\sim}10{\AA}$ thick on the properties of a spin valve. The back layers were Cu, Au, co-sputtered $Cu_xAu_{1-x}$, laminated $[Au/Cu]_n$. and bi-layer [Au/Cu]. When Au was added to the Cu, the resistance of the spin valve abruptly increased most likely due to impurity scattering. The GMR values were not increased significantly for all the structures. In the case of co-sputtered $Cu_xAu_{1-x}$, the changes in the resistance, ${\Delta}R$, was increased at a composition of ${\sim}Au_{0.5}Cu_{0.5}$. This increase in ${\Delta}R$ is due to increase in the resistance and not from the enhanced spin-dependent scattering. The structural analyses showed that the orthorhombic $Au_{0.5}Cu_{0.5}$ was formed in the back layer instead of the face-centered tetragonal $Au_{0.5}Cu_{0.5}$ as we expected. Thermal annealing over $400^{\circ}C$ may be required to have face-centered tetragonal in the $10{\AA}$ thick ultra-thin film. In the case of a laminated or bi-layered back layer, the properties of the spin valve were improved, which may be attributed to the increase in the mean free path of conduction electrons.

• 한국주조공학회지
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• 제41권1호
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• pp.3-10
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• 2021

알루미늄 합금과 주철의 복합주조 공정 중에는 주철로부터 철 성분이 용해되어 알루미늄 용탕에 혼입될 수 있으므로 다양한 Fe함유 금속간 화합물이 형성되며, 이로 인해 알루미늄 합금의 인장 특성이 크게 저하 될 수 있다. 반면 불순물로 첨가되는 Fe와 는 달리 Cu의 경우 알루미늄 합금의 기계적 물성을 향상시키기 위해 첨가되는 합금원소이다. 본 연구에서는 Fe와 Cu의 첨가로 인한 알루미늄 합금의 미세조직 및 인장특성의 변화를 조사하였다. 첨가된 Fe 함량이 1% 이상일 경우 조대한 Al₅FeSi 상과 같은 Fe 함유 화합물들이 다량 형성되어 인장 특성이 현저히 감소하는 것으로 나타났다. Cu가 첨가 된 알루미늄 합금의 경우 Al2Cu 상이 추가로 형성되었으며, 인장 강도가 뚜렷하게 향상되는 결과를 보였다.