• Title/Summary/Keyword: $SrCu_2O_2$

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Substrate effects on the characteristics of $YBa_2Cu_3O_{7-x}$ thin films prepared by RF magnetron sputtering (RF마그네트론 스퍼터링법으로 제조한 $YBa_2Cu_3O_{7-x}$전도체 박막의 특성에 대한 기판의 영향)

  • 신현용;박창엽
    • Electrical & Electronic Materials
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    • v.8 no.1
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    • pp.6-12
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    • 1995
  • High Tc superconducting YBa$_{2}$Cu$_{3}$$O_{7-x}$ thin films were prepared on various substrates by off-axis rf magnetron sputtering method to examine the substrate effects on the film structure and its R-T characteristics. The SEM analysis showed that the surface morphology of the grown YBa$_{2}$Cu$_{3}$O.sub 7-x/, film has different characteristic structure with different substrate used. The film on (100) SrTiO$_{3}$ substrate has critical current density of 3*10$^{5}$ A/cm$^{2}$ at 77K under zero magnetic field. The X-ray diffraction measurements revealed that the films on (100) SrTiO$_{3}$ substrate have mixed a-axis and c-axis normal to the substrate surface and the films on (100) MgO and ZrO$_{2}$/sapphire substrates have c-axis normal orientation to the substrate surface. However, YBa$_{2}$Cu$_{3}$$O_{7-x}$ films on (100) sapphire substrates showed no preferential orientation.ion.

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Effects of Substrate and Sintering Conditions on the Properties of Screen Printed Bi-Pb-Sr-Ca-Cu-O Superconduction Thick Films (Screen printing 방법에 의한 후막형 Bi-Pb-Sr-Ca-Cu-O 초전도체의 소결조건과 기판의 초전도성에 미치는 영향)

  • 김혜동;임호빈
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1990.10a
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    • pp.26-30
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    • 1990
  • Bi$\_$0.7/Pb$\_$0.3/Sr$_1$Ca$_1$Cu$\_$1.8/Ox thick films were screen printed on magnesia(MgO), silver and yttrium stabilized zirconia (YSZ) substrates and were sintered in a boat with cover to prevent the evaporation. The high-Tc phase increase and the low-Tc phase and Ca$_2$PbO$_4$ decrease with an increase in sintering temperature from 835$^{\circ}C$ to 860$^{\circ}C$. YSZ substrate interact strongly with the oxide resulting in poor superconductor, while the Ag and MgO substrates were satisfactory to make screen printed superconductors. The Bi$\_$0.7/Pb$\_$0.3/Sr$_1$Ca$_1$Cu$\_$1.8/Ox thick films screen printed both on Ag and MgO substrates show high Tc phase of ~85% and Tc of 96K.

Superconducting properties of layer-by-layer grown $YBa_{2}Cu_{3}O_{7}$ thin film prepared by pulsed laser deposition (펄스 레이저 증착법으로 layer-by-layer 성장시킨 $YBa_{2}Cu_{3}O_{7}$ 박막의 초전도특성)

  • Kim, In-Seon;Lim, Hae-Ryong;Kim, Dong-Ho;Park, Yon-Ki;Park, Jong-Chul
    • Journal of Sensor Science and Technology
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    • v.7 no.1
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    • pp.61-66
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    • 1998
  • High quality c-axis oriented $YBa_{2}Cu_{3}O_{7}$ films were prepared using the pulsed laser deposition on $SrTiO_{3}$(100) substrate. The atomically smooth $SrTiO_{3}$surface with terraces one unit cell in height could be obtained by a high temperature annealing. $YBa_{2}Cu_{3}O_{7}$ thin films deposited on the substrates exhibited layer-by-layer growth with a c-axis unit cell height. $YBa_{2}Cu_{3}O_{7}$ thin films thus prepared showed critical temperature ${\ge}90$ K with transition width ${\le}0.6$ K, room temperature resistivity of ${\sim}300{\mu}{\Omega}cm$, and critical current density ${\sim}4.6{\times}10^{6}A/cm^{2}$ at 77 K.

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Low Temperature Sintering of (Bi1/2Na1/2)TiO3-SrTiO3 Ceramics and Their Ferroelectric and Piezoelectric Properties (BNT-ST 세라믹스의 저온 소결과 강유전 및 압전 특성)

  • Hyunhee Kwon;Ga Hui Hwang;Chae Il Cheon;Ki-Woong Chae
    • Journal of Sensor Science and Technology
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    • v.32 no.4
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    • pp.238-245
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    • 2023
  • 0.75(Bi1/2Na1/2)TiO3-0.25SrTiO3 (BNT-25ST) ceramics with high densities were successfully prepared at a sintering temperature of 1,000℃ by adding a mixture of 1 mol% CuO and 0.5 mol% Na2CO3 or 0.5 mol% CuO and 0.25 mol% Na2CO3. Double polarization-electric field (P-E) hysteresis curves and sprout-shaped bipolar strain-electric field (S-E) hysteresis curves with small negative strains were observed in the pristine and CuO-added BNT-25ST ceramics whereas the Na2CO3-added sample showed similar P-E and S-E curves to a typical ferroelectric. The pristine BNT-25ST ceramics showed an extremely large strain and a large-signal piezoelectric strain constant (d33*): 0.287 % at 80 kV/cm and 850 pm/V at 20 kV/cm. Similar values, 0.248 % at 80 kV/cm and 655 pm/V at 20 kV/cm, were obtained in the CuO-added sample. However, the pristine and CuO-added samples showed large hysteresis in unipolar S-E curves at an electric field of less than 20 kV/cm. The Na2CO3-added sample showed smaller values of the strain and d33* but displayed a linear change and small hysteresis in the unipolar S-E curve. The co-added sample with CuO and Na2CO3 displayed intermediate P-E and S-E hysteresis curves.

Fabrication of Bi System Superconducting Films on Cu Tape with Melt-Quenched Cu-free Materials (Cu-free 비정질체를 이용한 동 테이프 위의 Bi계 초전도 후막 제조)

  • Sung, Tae-Hyun;Han, Sang-Chul;Han, Young-Hee;Lee, Jun-Seong;Kim, Sang-Joon
    • 한국초전도학회:학술대회논문집
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    • v.9
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    • pp.315-318
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    • 1999
  • Bi$_{2}Sr_{2}CaCu_{2}O_{\delta}$ superconducting films were rapidly fabricated on copper tape by liquid reaction between a Cu-free precursor and Cu tape (LiReac-PreCu) method. Those thick films were well oriented along the c-axis. The precursor was made by melt-quenched technology using twin roller. The melt-quenched films were transparent and glossy yellow in appearance. These films which were the compostion of Bi$_2SrCaO_y$, Bi$_3Sr_2CaO_z$ were placed on copper tape and then heated at various temperatures for several minutes in air. They were analyzed using X-ray powder diffraction, SEM, a DC four-probe method. The mechanism of superconducting phase formation . from the melt-quenched precursor on Cu tape was studied

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The Effect of Substrate Surface Treatment by Ion Bombardment on Y-Ba-Cu-O Thin Film Growth (이온충돌에 의한 기판 표면처리가 Y-Ba-Cu-O 박막의 성장에 미치는 영향)

  • 김경중;박근섭;박용기;문대원
    • 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.

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The magnetic properties in Bi$_2$Sr$_2$CaCu$_2$O$_8$ single crystal with columnar defects

  • Lee, C.W.;Shim, S.Y.;Ha, D.H.;Kim, D.H.;Lee, T.W.
    • 한국초전도학회:학술대회논문집
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    • v.10
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    • pp.103-106
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    • 2000
  • We have studied the magnetic properties in Bi$_2$Sr$_2$CaCu$_2$O$_8$ single crystal with columnar defects using micro Hall-probe array. We found that fold profiles inside sample were similar to the Bean's critical state model from the magnetic hysteresis measurement. In the magnetic relaxation measurement, the normalized relaxation rates were maximum near the center and decreased toward the edge of the sample expect zero gauss. The relaxation rates as a function of the temperature were maximum near the 40K and rapidly decreased both sides of the peak.

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Geochemical Dispersion and Enrichment of Fluvial Sediments Depending on the Particla Size Distribution (입도분포에 따른 하상퇴적물의 지구화학적 분산 및 부화)

  • 이현구
    • Economic and Environmental Geology
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    • v.32 no.3
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    • pp.247-260
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    • 1999
  • Geochermical characteristics of the fluvial sediments deprnding on particle size distribution size were investigated in the respect of majir, minor and rare eath element chemisitry. Ratios of $Al_{2}O_{3}/Na_{2}O$ and $K_{2}O/Na_{2}O$ of the sediments show the homogeneous valus, and partly positive correlation with $SiO_{2}/Al_{2}O_{3}$, respecively. Characteristics of minor element ratios (V/Ni, Cr/V, Ni/Co and Zr/Hf)are within the lower and narrow range. Thesesuggested that sediment sources may be acidic to intermediate granitic rock, and may be explained by simple weathering and sedimentation. With increasing SiO2 contents, concentrations of $Al_{2}O_{3}$, $Fe_{2}O_{3}$, CaO and MgO decreased, but those of $K_{2}O$ and $Na_{2}O$ increased, Concentrations of Ba, Be, Cs, Cu, Li, Ni, Sr, V and Zr show comparatively normal negative and some positive trends. Compared with the mean composition of granite, concentrations of $Al_{2}O_{3}$, $Fe_{2}O_{3}$, MnO, CaO and MgO in the sediments of the study area were highly enriced. Among some minor and rare earth elements, concentrations of As, Cd, Cu, and V were enriched, but those of Be, Ce, Rb, Sc, Sr and Zn were depleted when compared with average composition of granite. By decreasing of particle size fractions, SiO2, Rb and Sr conterts decreased, but concentrations of $Al_{2}O_{3}$, $Fe_{2}O_{3}$, CaO, MgO, $TiO_{2}$, MgO, $P_{2}O_{5}$, Be, Cu, Hf, Pb, V and Zr increased. From the correlations between particle size fractions and element concenreations, some elements of $Fe_{2}O_{3}$, CaO, MgO, $P_{2}O_{5}$, Cu, Ni, Zn and Zr showed typical trends in the secondary contramination sediments. These trends are typically shown under 100 mesh fractions. It indicates that the fraction of minus 100 mesh is the optimum size fraction for geochemical and environmental survey.

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