Preparation of YBCO with additives of PbO, $BaPbO_3$ and its Superconducting Properties

Zhanguo, Fan,Soh, Dae-Wha The Speleological Society 2007 동굴 Vol.78 No.-

The melting temperature and critical temperature (Tc) of $YBa_2Cu_3O_x$ with deferent content impurities of PbO and $BaPbO_3$ were studied. When the PbO was used as addition in $YBa_2Cu_3O_x$, although the melting point could be reduced, the superconductivity (the transition wide, ${\Delta}T_c$) became poor. From the XRD pattern of the sintered mixture of $YBa_2Cu_3O_x$ and PbO it was known that there is a reaction between $YBa_2Cu_3O_x$ and PbO, and the product is $BaPbO_3$. In the process of the reaction the superconducting phase of $YBa_2Cu_3O_x$ was decreased and in the sample $BaPbO_3$ became the main phase. Therefore the superconductivity was reduced. $BaPbO_3$ was chosen as the impurity for the comparative study. The single phase $BaPbO_3$ was synthesized by the simple way from both mixtures of $BaCO_3$ and PbO, $BaCO_3$ and $PbO_2$. Deferent contents of $BaPbO_3$ (10%, 20%, 30%) were added in the $YBa_2Cu_3O_x$. By the phase analysis in the XRD patterns it was proved that there were not reactions between $YBa_2Cu_3O_x$ and $BaPbO_3$. When $BaPbO_3$ was used as impurity in $YBa_2Cu_3O_x$ the superconductivity was much better than PbO as impurity in $YBa_2Cu_3O_x$. But the melting point of $YBa_2Cu_3O_x$ with $BaPbO_3$ could not be found when the temperature was lower than $1000^{\circ}C$ in the DTA measurement.

Superconducting Film with Submicron YBCO powder by EPD

Fan, Zhanguo,Soh, Deawha 明知大學校 産業技術硏究所 2004 産業技術硏究所論文集 Vol.23 No.-

The submicron YBa_(2)Cu_(3)O_(x) powder was prepared by the sol-gel method. The particle size is distributed from 0.2 to 1.2 ㎛, which benefits to eliminate the micro-cracks formed in the YBa_(2)Cu_(3)O_(x) films deposited by electrophoresis. The powder was single phase of YBa_(2)Cu_(3)O_(x) examined by X-ray diffraction. In the sol-gel process the citrate gel was formed from citric acid and nitrate solution of Y_(2)O_(3), Ba(NO_(3))_(2) and CuO. When pH values were adjusted to 6.4-6.7, Ba(NO_(3))_(2) could be dissolved in the citrate solution completely. Appropriate evaporative temperature of the sol-gel formation is discussed. Acetone is used as electrophoretic solution, in which some water and iodine (0.2 g/1) and polyethylene glycol (2 vol.%) are added. The concentration of YBa_(2)Cu_(3)O_(x) powders is 20 g/l. The thickness of deposited film could be more than 50 ㎛ in 3 minutes of depositing time. The most EPD films could be 90 K zero resistance and the Jc values were over 1000 A/cm^(2)(0 H, 77 K).

보조진동전계를 이용한 전기영동전착 YBCO 초전도 선재의 제작 연구

전용우,樊占國,소대화 明知大學校 産業技術硏究所 2004 産業技術硏究所論文集 Vol.23 No.-

In order to improve the surface uniformity and the conduction properties of the fabricated YBCO thick films, a system that applies alternating field vertically to the EPD field has been developed for the first time and applied to the electrophoretic deposition process. The applied alternating electric field caused a force to be exerted on each YBCO particle and resulted in a shaking of the particle in the direction of applied electric field, accomplishing a uniform particle orientation. For commercial utilization and efficiency, in this dissertation, alternating voltage of 25∼120 V/cm in frequency of 60Hz was proposed to apply it as a subsidiary source for shaky-flow deposition so that the fabricated thin film showed uniform surface morphology with less voids and cracks and T_(c,zero) of 90 K and the critical current density of 3419 A/cm_(2).

Carbon Contents and Its Effects on the Supercondutivities of Bi₂Sr₂CaCu₂Ox compound

Wang, Wenhu,Fan, Zhanguo,Shan, Yuqiao,Soh, Deahwa 明知大學校 産業技術硏究所 1997 産業技術硏究所論文集 Vol.16 No.-

Bi₂Sr₂CaCu₂Ox was sintered by the conventional solid state reaction method. The samples were annealed in different atmosphere in order to examine the influence of atmospheres on the carbon contents in the Bi₂Sr₂CaCu₂Ox compound. The lowest carbon content in Bi₂Sr₂CaCu₂Ox could be attend when the sample was annealed in O₂at 800℃ for 100 hours. The CO₂ in air could pollute the samples and increase the carbon content in the sintering process. The critical current density of the Bi₂Sr₂CaCu₂Ox samples will decrease with the increasing carbon contents in the samples. When the carbon content was over 0.84wt%, the Bi₂Sr₂CaCu₂Ox became non-superconductor. The impurity carbon will deposit in the grain boundary which makes critical current density lower.

YBaCuO 초전도 미세 분말 연구 및 전기영동전착 초전도 선재 제작 연구

박성범,樊占國,소대화 明知大學校 産業技術硏究所 2004 産業技術硏究所論文集 Vol.23 No.-

The submicron YBa_(2)Cu_(3)O_(x) powder was prepared by the sol-gel method. The particle size is distributed from 0.2 to 1.0 ㎛, which benefits to eliminate the micro-cracks formed in the YBa_(2)Cu_(3)O_(x) films deposited by electrophoresis. The powder was single phase of YBa_(2)Cu_(3)O_(x) examined by X-ray diffraction. In the sol-gel process the citrate gel was formed from citric acid and nitrate solution of Y_(2)O_(3), Ba(NO_(3))_(2) and CuO. When pH values were adjusted to 6.4~6.7, Ba(NO_(3))_(2) could be dissolved in the citrate solution completely. Appropriate evaporative temperature of the sol-gel formation is discussed. After the heat treatment the transition temperature(T_(c)) and critical current density(J_(c)) of the YBa_(2)Cu_(3)O_(x) samples made of the submicron powder were measured.

Fine YBaCuO Superconducting Powder Prepared by Sol-gel Method

Soh, Deawha,Zhanguo, Fan 明知大學校 産業技術硏究所 2003 産業技術硏究所論文集 Vol.22 No.-

Abstract - In order to get proper original suspension for the electophoresis process of making YBaCuO films, YBaCuO superconductor powder was prepared with the Sol-gel method. The composition of the powder was analyzed by X-ray diffraction, which was identified as YBa_2Cu_3O_7-X(Y123) phase. The form of YBaCuO single particle was showed to be spherical by scanning electronic microscope and its size was among 0.2-1 ㎛. The critical transition temperature (T_c) and the critical current density (J_c) were measured with the four-probe method. The T_c was about 91 K, and the J_c was 5-30 A/㎠.

Water Caves of Liaoning in Northeastern China -Shenyang Water Cave and Benxi Water Cave-

Soh Dea Wha,Fan Zhanguo The Speleological Society 2004 동굴 Vol.65 No.-

To introduce the typical water caves of the northeastern district in China, the Shenyang Water Cave located in the Shenyang city and the Benxi Water Cave located in the Benxi city of the Liaoning province of the northeastern part of China are presented. The caves are very big and long, and the water flows in the cave to drive the motor boat for tourist watching the beautiful sight in the caves through the year. The geological information and the beautiful internal sight of views in the caves are introduced.

EPD Superconductor Film with Submicron YBCO on Ag Alloy

Soh, Dea-Wha,Fan, Zhanguo,Jeon, Yong-Woo The Speleological Society 2006 동굴 Vol.76 No.-

The submicron $YBa_2Cu_3O_x$ powder was prepared by the sol-gel method. The particle size is distributed from 0.2 to 1.0 ${\mu}m$, which benefits to eliminate the micro-cracks formed in the $YBa_2Cu_3O_x$ films deposited by electrophoresis. The powder was single phase of $YBa_2Cu_3O_x$ examined by X-ray diffraction. In the sol-gel process the citrate gel was formed from citric acid and nitrate solution of $Y_2O_3$, $Ba(NO_3)_2$ and CuO. When pH values were adjusted to 6.4-6.7, $Ba(NO_3)_2$ could be dissolved in the citrate solution completely. Appropriate evaporative temperature of the sol-gel formation is discussed. Acetone is used as electrophoreticsolution, in which some water and iodine (0.2 g/1) and polyethylene glycol (2 vol. %) are added. The concentrations of $YBa_2Cu_3O_x$ powders is 20g/l. The thickness of deposited film could be more than 50 ${\mu}m$ in 3 minutes of depositing time. The most EPD films could be 90K zero resistance and the Jc values were over 1000A/cm2 (0 H, 77 K).

Carbon Content Influences on Superconductivity of BSCCO HTS by SSR and SHS

Soh, Dea-Wha,Korobova, Natalya,Zhanguo, Fan 明知大學校 産業技術硏究所 2003 産業技術硏究所論文集 Vol.22 No.-

Abstract - Bi_2Sr_2CaCu_2Ox was prepared by the conventional method of Solid State Reaction(SSR) and Self-propagating High-temperature Synthesis(SHS) method. The samples were annealed in different atmosphere in order to examine the influences of atmospheres on the carbon contents in the Bi_2Sr_2CaCu_2Ox compound. The lowest carbon content in Bi_2Sr_2CaCu_2Ox could be attended when the sample was annealed in O_2 at 800℃ for 100 hours. The CO_2 in air pollute the samples and increase the carbon content in the sintering process. The critical current density of the Bi_2Sr_2CaCu_2Ox samples will decrease with the increasing carbon contents in the samples. The impurity carbon will deposit in the grain boundary, which makes lower critical current density.

YbBaCuO 초전도체의 텍스쳐 조직 성장

소대화,번점국 ( Dea Wha Soh,Fan Zhanguo ) 한국전기전자재료학회 1997 한국전기전자재료학회 춘계학술대회논문집 Vol.1997 No.0