• Progress in Superconductivity
• /
• 제5권2호
• /
• pp.94-97
• /
• 2004

Step-edge Josephson junctions (SEJ) have been fabricated on sapphire substrates with in situ deposited films of CeO$_2$ buffer layer and YBa$_2$Cu$_3$O$_{7}$ films on the low angle steps. Direct coupled SQUID magnetometers with the SEJ were formed on 1 cm X 1 cm R-plane sapphire substrates. Typical 5-${\mu}{\textrm}{m}$-wide Josephson junctions have R$_{N}$ of 3 Ω and I$_{c}$ of 50 $mutextrm{A}$ at 77 K. The direct coupled SQUID magnetometers were designed to have pickup coils of 50-${\mu}{\textrm}{m}$-wide 16 parallel loops on the 1 cm X 1 cm substrates with outer dimension of 8.8 mm X 8.8 mm. The SEJ SQUID magnetometers exhibit relatively low 1/f noise even with dc bias control, and could be stably controlled by flux-locked loops in the magnetically disturbed environment. Field noise of the do SQUID was measured to be 200∼300 fT/Hz$^{1}$2/in the white noise region and about 2 pT/Hz$^{1}$2/ at 1 Hz when measured with dc bias method.hod.d.

• Progress in Superconductivity
• /
• 제3권1호
• /
• pp.60-64
• /
• 2001

We have studied properties of step-edge Junction prepared with crystal orientation of sapphire substrate. The Step on sapphire substrates fabricated by conventional photolithography method and Ar ion milling method. $CeO_2$ buffer layer and in-situ YBCO thin film were deposited on the stepped sapphire substrates by a pulsed laser deposition method with the predetermined optimized condition. The step angle was centre fled low angle of about $25^{\circ}$. The YBCO film thickness was varied to obtain various thickness ratios of the film to the step height in a range from 0.7 to 1.2. I-V curves of junction were showed RSJ-behavior, double junction structure, and hysteresis due to the crystal orientation of substrate.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
• /
• pp.104-106
• /
• 2003

다층의 산화물 박막으로 이루어진 coated conductor의 제조를 위하여 각층의 증착조건이 최적화되어야 한다. 가공/열처리를 통하여 2축배향성을 가지는 Ni 금속 기판위에 $Y_2O_3$, YSZ, $CeO_2$ 등의 산화물 완충층을 증착한 후 초전도층인 YBCO를 증착하였다. 12도와 8도의 in-plane fwhm (full width at half maximum)과 out-of-plane fwhm을 가지는 Ni 기판을 이용하여 13도와 4.5도의 in-plane 및 out-of-plane fwhm을 가지는 YBCO coated conductor를 제조하였다. 임계온도 (Tc), 임계전류 (Ic), 및 임계전류밀도 (Jc) 는 각각 84K, 3.3A, 및 $310,000\;A/cm^2$ 이었다.

• 한국초전도저온공학회:학술대회논문집
• /
• 한국초전도저온공학회 2002년도 학술대회 논문집
• /
• pp.135-137
• /
• 2002

In the favor of adjusting microwave signal, Hairpin type Filter, which delay microwave signal enough to several nanosecond, is a key component. One of the main advantage in using Hairpin type Filter is a conveniency for equipping with Delay Module, and because of having a wide bandwidth, Hairpin type Filter can be designed to satisfy the most applications. In this work, we attempted to estimate the delay time in a superconductive hairpin type filter A software to synthesize even and odd order equiripple hairpin type filter has been developed. This software arbitrarily locate its transfer zeros making symmetric of asymmetric amplitude response and equalizing group delay. Borland C++ compiler has been used. The program was designed to run under MS-DOS, Window 98, Window 2000. The program optimizes the position of the transfer function zeros in order to fulfill the group delay specification masks. We designed and fabricated a hairpin type HTS 2-pole microstrip bandpass filter to operate at 5.8Ghz. The fabrication method was pulsed laser deposition and YBCO films were deposited on sapphire substrates with a Ce$O_{2}$ thin layer as a buffer layer. We also developed a new style hairpin type filter by using interdigitide inner-pole. Compared to the same size regular hairpin type filters, our filters had a lower center frequency.

• 한국초전도ㆍ저온공학회논문지
• /
• 제6권4호
• /
• pp.13-16
• /
• 2004

Three film deposition systems (pulsed laser deposition, sputtering, and evaporation) equipped with reel-to-reel metal tape moving apparatus were installed and used to make meter-long coated conductor. Buffer architecture of $CeO_2/YSZ/Y_2O_3$ was deposited on Ni alloy using sputtering, evaporation, and PLD. YBCO superconducting layer was continuously deposited on buffered metal tape by PLD. End-to-end critical current ($I_c$) of 107 A at 77 K, self-field has been achieved in 1 em-wide tape (thickness 0.6∼1.0${\mu}{\textrm}{m}$, tape moving speed 54∼72 cm/hr) over 1 meter length.

• 한국세라믹학회지
• /
• 제48권5호
• /
• pp.479-484
• /
• 2011

In this paper, investigations of thick film $La_{0.75}Sr_{0.25}Ga_{0.8}Mg_{0.16}Fe_{0.04}O_{3-{\delta}}$ (LSGMF) cells fabricated via spin coating on either NiO-YSZ anode or $La_{0.7}Sr_{0.3}Ga_{0.6}Fe_{0.4}O_3$ (LSGF) cathode substrates are presented. A La-doped $CeO_2$ (LDC) layer is inserted between NiO-YSZ and LSGMF in order to prevent reactions from occurring during co-firing. For the LSGF cathode-supported cell, no interlayer was required because the components of the cathode are the same as those of LSGMF with the exception of Mg. An LSGMF electrolyte slurry was deposited homogeneously on the porous supports via spin coating. The current-voltage characteristics of the anode and cathode supported LSGMF cells at temperatures between $700^{\circ}C$ and $850^{\circ}C$ are described. The LSGF cathode supported cell demonstrates a theoretical OCV and a power density of ~420 mW $cm^2$ at $800^{\circ}C$, whereas the NiO-YSZ anode supported cell with the LDC interlayer demonstrates a maximum power density of ~350 mW $cm^2$ at $800^{\circ}C$, which decreased more rapidly than the cathode supported cell despite the presence of the LDC interlayer. Potential causes of the degradation at temperatures over $700^{\circ}C$ are also discussed.

• Journal of Electrochemical Science and Technology
• /
• 제10권3호
• /
• pp.335-343
• /
• 2019

In this study, $Sr_2Ni_{1.8}Mo_{0.2}O_{6-{\delta}}$ (SNM) with a double perovskite structure was investigated as an alternative anode for use in the $CH_4$ fuel in solid oxide fuel cells. SNM demonstrates a double perovskite phase over $600^{\circ}C$ and marginal crystallization at higher temperatures. The Ni nanoparticles were exsolved from the SNM anode during the fabrication process. As the SNM anode demonstrates poor electrochemical and electro-catalytic properties in the $H_2$ and $CH_4$ fuels, it was modified by applying a samarium-doped ceria (SDC) coating on its surface to improve the cell performance. As a result of this SDC modification, the cell performance improved from $39.4mW/cm^2$ to $117.7mW/cm^2$ in $H_2$ and from $15.9mW/cm^2$ to $66.6mW/cm^2$ in $CH_4$ at $850^{\circ}C$. The mixed ionic and electronic conductive property of the SDC provided electrochemical oxidation sites that are beyond the triple boundary phase sites in the SNM anode. In addition, the carbon deposition on the SDC thin layer was minimized due to the SDC's excellent oxygen ion conductivity.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
• /
• pp.634-638
• /
• 2003

We reported the a-Si crystallization using a XeCl excimer laser annealing on the plastic substrate. The poly-Si film is able to grow in the low temperature and light substrate like a plastic. For the preparation of sample, substrate is cleaned by organic liquids. The film of $CeO_{2}$ layer as the buffer layer was grown by sputtering methods. After a-Si film deposition using ICPCVD, the film was crystallized by XeCl excimer laser. In this paper, we present the crystallization properties of a-Si on the plastic substrate

• 방사성폐기물학회지
• /
• 제18권3호
• /
• pp.337-346
• /
• 2020

Two commonly used ceramics in molten salt research are alumina and mullite. The two ceramics were exposed to a combination of rare earth chlorides (YCl₃, SmCl₃, NdCl₃, PrCl₃, and CeCl₃; each rare earth chloride of 1.8 weight percent) in LiCl-KCl at 773 K for approximately 13 days. Scanning electron microscopy with wave dispersion spectra was utilized to investigate a formation layer or deposition of rare earths onto the ceramic. Only the major constituents of the ceramics (Al, Si, and O₂) were observed during the wave dispersion spectra. X-ray fluorescence was used as well to determine concentration changes in the molten salt as a function of ceramic exposure time. This study shows no evidence of ionic exchange or layer formation between the ceramics and molten chloride salt mixture. There are signs of surface tension effects of molten salt moving out of the tantalum crucible into secondary containment.

• Progress in Superconductivity
• /
• 제6권1호
• /
• pp.74-78
• /
• 2004

YBCO coated conductor is one of the most promising materials as a new generations wire especially for practical power applications. In this work, $YBa_2$$Cu_3$$O_{7}$ -$\delta$/(YBCO) coated conductors (CC) were deposited by pulsed laser deposition (PLD) from buffer layers to superconducting layer on hi-axially textured metal tape. The oxide multilayer buffered substrate of architectures of $CeO_2$/$YSZ/Y_2$$O_3$ was fabricated by PLD at steady status. Then YBCO layer was deposited on RABiTS substrate by stationary and reel-to-reel (R2R) continuous process and we compared with deposition conditions of both processes. The degree of texture of each layer was investigated using X-ray diffraction including $\theta$-2$\theta$ scans, $\omega$-scans and $\Phi$-scans analysis. Their surface morphology was observed by scanning electron microscopy (SEM). The FWHM of the X-ray $\Phi$-scans and $\Phi$-scans indicated that YBCO and buffer layers closely replicate the in-plane and out-of-plane texture of metal tape. Critical current (Ic) at 77 K, self-field of 75.8 A/cm-width, critical temperature (Tc) of 85 K, and critical current density (Ic) of 3.7 MA/$\textrm{cm}^2$ were measured from coated conductor deposited by stationary process. And coated conductor deposited by R2R continuous process had Ic of 57.5 A/cm-width, Tc of 86.5 K and Jc of 2.0 MA/$\textrm{cm}^2$. The film also exhibits a homogeneous and dense surface morphology.