• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2002년도 학술대회 논문집 전문대학교육위원
• /
• pp.49-51
• /
• 2002

In this thesis, Josephson junction using high-Tc superconducting multi-layer thin film has been fabricated by on-axis RF magnetron sputtering method. And, the characterizations were performed by X-ray diffraction, SEM and the measuring system of critical current density. The physical properties of multi-layer superconducting thin films were also analyzed with the measured results. To fabricate the multi-layer superconducting thin films, the optimum partial pressure of Argon and Oxgen and the temperature of substrate were measured. Also, YBaCuO thin film was grown on MgO and $SrTiO_3$ substrates by rf-sputtering and LGO thin film of 30 A was epitaxially grown on the YBaCuO thin film as a josephson junction with the same condition. The schottky barrier at the contact surface between YBaCuO/LGO and YBaCuO/Au and the energy gap of 0.5 ${\sim}$ 0.6 mV in Nb were observed from the dI/dV-V of YBaCuO/LGO/Au/Nb and YBaCuO/Au/Nb.

• 한국전기전자재료학회논문지
• /
• 제13권11호
• /
• pp.959-962
• /
• 2000

We have fabricated good quality superconducting YBa$_2$Cu$_3$$O_{7-x}$(YBCO) thin films on Hastelloy(Ni-Cr-Mo alloys) metallic substrates with CeO$_2$and BaTiO$_3$buffer layers in-situ by pulsed laser deposition in a multi-target processing chamber. YBCO film with CeO$_2$single buffer layer shows T$_{c}$ of 71.64 K and the grain size less than 0.1${\mu}{\textrm}{m}$. When BaTiO$_3$ is used as a single buffer layer, the grain size of YBCO is observed to be larger than that of YBCO/CeO$_2$by 200 times and the transition temperature of the film is enhanced to be about 84 K. CeO$_2$/BaTiO$_3$double buffer layer has been adopted to enhance the superconducting properties, which results in the enhancement of the critical temperature and the critical current density to be about 85 K and 8.4$\times$10$^4$ A/$\textrm{cm}^2$ at 77 K, respectively mainly due to the enlargement of the grain size of YBCO film.ilm.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
• /
• pp.570-574
• /
• 1999

In this paper, by using the electrophoresis, preparation of YBCO superconducting wire deposited on metal Ag base wire was studied with its Properties. YBCO Powder could be prepared by solid state reactions with calcining and sintering processes. Superconducting wire prepared on metal Ag wire used as cathode of deposition base could be also fabricated in the YBCO/acetone-dispersed solution to obtain several tens of re thick films. And then it could be used as superconducting wire for measurement after calcination, sintering and oxygen absorption processes. In the process of film deposition, a catalyst I$_2$added into the suspension solution was very useful for preparing thick film of YBCO, and BaF$_2$ of additive material was also necessary for preparing crack-free wire of YBCO superconductor. As a result, YBCO superconducting wire added 2~3wt.% of BaF$_2$\ulcorner with catalyst, 12 had better deposition condition for uniform and dense YBCO wires, and critical current density, Jc was calculated at the value of 1,458A/$\textrm{cm}^2$(more than 10$^{3}$A/$\textrm{cm}^2$ ,77K, o[T]) of 30${\mu}{\textrm}{m}$ thick sample by 4 point prove method.

• 한국초전도ㆍ저온공학회논문지
• /
• 제26권1호
• /
• pp.5-9
• /
• 2024

This study investigated the effect of Kr ion beam irradiation on the superconducting properties of Nb thin films, which are known for their high superconducting transition temperature (T_c) at ambient pressure among single elements. Using the Stopping and Range of Ions in Matter (SRIM) program, we analyzed the distribution of Kr ions and displacement per atom (DPA) after irradiation, finding a direct correlation between irradiation amount and DPA. In samples with stronger beam energy, deeper ion penetration, fewer ions remained, and higher DPA values were observed. X-ray diffraction (XRD) revealed that the Nb (110) peak at 38.5° weakened and shifted with increasing irradiation. T_c decreased in all samples after irradiation, more significantly in those with higher beam energy. Irradiation raised resistivity of the film and lowered the residual-resistivity ratio (RRR). AC susceptibility measurements were also consistent with these findings. This research could potentially lead to more efficient and powerful superconducting devices and a better understanding of superconducting materials.

• Transactions on Electrical and Electronic Materials
• /
• 제6권4호
• /
• pp.186-189
• /
• 2005

We have fabricated superconducting HTSC ceramic thick films by chemical process. c-axis oriented HTSC thick films have been attempted bi-axially textured Ni tapes. The x-ray diffraction pattern of the HTSC thick films contained superconducting phase crystal. The critical temperature and critical current density was 110K.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2002년도 추계종합학술대회
• /
• pp.796-799
• /
• 2002

BSCCO thin films are fabricated via a co-deposition process at an ultra-low growth rate using ion beam sputtering. The sticking coefficient of Bi element exhibits a characteristic temperature dependence. This temperature dependence of the sticking coefficient was explained consistently on the basis of the evaporation and sublimation processes of Bi$_2$O$_3$.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1994년도 추계학술대회 논문집 학회본부
• /
• pp.212-214
• /
• 1994

At recent time, superconducting technology makes it possible to develop various devices using strong magnetic fields. As increasing with devices using high magnetic fields, magnetic shielding technology is essential in order to get high efficiency. Therefore it is necessary to establish production method and clear characteristics of suitable shielding materials. Usually, ferromagnetic metal has been used for shielding of high magnetic fields up to the present time. Instead of heavy ferromagnetic metal, we can acquire better upgraded shielding system by using of very light superconducting thin film that has a perfect diamagnetism. We would like to study basic characteristics of NbTi thin film produced by RF sputtering, investigated morphology and crystal structure of NbTi thin film by SEM and XRD, identified superconductivity measuring by critical current.

• 한국초전도학회:학술대회논문집
• /
• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
• /
• pp.392-396
• /
• 1999

Superconducting YBa$_2Cu_3O_{7-{\delta}}$(YBCO) thin films were grown on Hastelloy(Ni-Cr-Mo alloys) with CeO$_2$ buffer layer in-situ by pulsed laser deposition in a multi-target processing chamber. To apply superconducting property on power transmission line, we have deposited YBCO thin film on flexible metallic substrate. However, it is difficult to grow the YBCO films on flexible metallic substrates due to both interdiffusion problem between metallic substrate and superconducting overlayers and non-crystallization of YBCO on amorphous substrate. It is necessary to use a buffer layer to overcome the difficulties. We have chosen CeO$_2$ as a buffer layer which has cubic structure of 5.41 ${\AA}$ lattice parameter and only 0.2% of lattice mismatch with 3.82 ${\AA}$ of a-axis lattice parameter of YBCO on [110] direction of CeO$_2$ In order to enhance the crystallization of YBCO films on metallic substrates, we deposited CeO$_2$ buffer layers with varying temperature and 02 pressure. By XRD, it is observed that dominated film orientation is strongly depending on the deposition temperature of CeO$_2$ layer. The dominated orientation of CeO$_2$ buffer layer is changed from (200) to(111) by increasing the deposition temperature and this transition affects the crystallization of YBCO superconducting film on CeO$_2$ buffered Hastelloy.

• Transactions on Electrical and Electronic Materials
• /
• 제5권5호
• /
• pp.199-203
• /
• 2004

Superconducting B $i_2$S $r_2$C $a_{n-l}$C $u_{n}$ $O_{x}$(n=2～4) thin films were prepared by single target DC-magnetron sputtering. And, that was compared with the B $i_2$S $r_2$C $a_{n-l}$C $u_{n}$ $O_{x}$(n=1～3) thin film fabricated by using the ion beam sputtering. Phase intergrowth among n=2-3, 3-4 and 4-5 phases was observed. The molar fraction of each phase in the mixed crystal of the deposited films was determined by x-ray diffraction analyses and investigated as a function of $O_2$ gas pressure during sputtering. We investigated the changes of the superconducting properties by molar fraction of each phase. Also, the thin film surface observation was carried out by atomic force microscope. The images show the average particle size decreases, and the distribution density of particles on the film surface was to increase with lower gas pressures. The fabrication conditions for selective growth of the single n=2, 3 and 4 phases in BiSrC $a_{n-l}$C $u_{n}$ $O_{x}$(n=2～4) thin film are discussed.e discussed.ussed.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 센서 박막재료 반도체재료 기술교육
• /
• pp.141-144
• /
• 2002

We present current limiting properties of 1.2kV/70A superconducting fault current limiter based on YBCO thin films. This is consisted of 6 wafers (3 parallel ${\times}$ 2 serial connection) with 4 inch-diameter YBCO thin film. The quench current Iq of the switching elements vary between 33.9 and 35.6 A. Within the difference of 0.5 A in the sum of quench current Iq in two stacks, the serial connection of the stacks showed the simultaneous quench behavior in applied power of 1.2 kV /70 A.