Browsing by Author "Du, C. H."

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A Superconducting Magnetization System With Hybrid Superconducting Wire for the Study and Application of Superconductivity
(2012-06-01)
Chen, S. D.
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Yu, Y. T.
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Jan, J. C.
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Lin, F. Y.
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Hwang, C. S.
For the study of high-temperature superconductors and for the application of superconductivity, a superconducting high-field magnetization system with a hybrid superconducting coil was designed. This coil is composed of superconducting wires of three kinds-HTS YBCO 2G-wire, high-field and low-field NbTi wires. Three principal purposes of building this system are to inspect the characteristics of disk-shape bulk YBCO, to develop a HTS-bulk undulator, and to magnetize a portable HTS-bulk high-field magnet for application to a resonant X-ray scattering experiment. With four steps of temperature decrease, a two-stage GM-type cryocooler and liquid nitrogen provide cooling for the magnetization system. The hybrid superconducting coil, two cryogenic systems for the magnetization system and the portable HTS-bulk magnet, and the control and monitor systems that were designed are discussed.
Design of a HTS Magnet for Application to Resonant X-Ray Scattering
(2011-06-01)
Chen, S. D.
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Yu, Y. T.
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Huang, Z. W.
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Jan, J. C.
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Hwang, C. S.
In material research, the characteristics of novel materials vary greatly with the environment. A magnet with a strong field will be developed for an experimental station for resonant X-ray scattering to investigate the magnetic properties of materials. This magnet will be developed with high-temperature superconductor (HTS) bulk YBa(2)Cu(3)O(7) and magnetized with a HTS coil magnet wound with 2G HTS wire. HTS (RE) BCO will be selected to construct the coil of this magnet. Both the bulk and coil magnets will be assembled on the same movable system. The bulk HTS magnet will provide flux density greater than 4 T with a gap 34 mm that can accommodate the sample holder of the experimental station. The bulk magnet will be cooled with cryocoolers to 29 K and the coil magnet to 4.2 K; the coil magnet is separable from the bulk magnet after the field is trapped. We describe the concept of the magnetic-field calculation, the overall design of these magnets, and the cooling algorithm for the bulk HTS magnet system.
Determination of the microstructure of Eu-treated ZnO nanowires by x-ray absorption
(2010-02-08)
Huang, W. L.
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Labis, J.
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Ray, S. C.
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Liang, Y. R.
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Pao, C. W.
X-ray absorption near-edge structure (XANES), extended x-ray absorption fine structures (EXAFS), and photoluminescence measurements were used to elucidate the microstructural and photoluminescence properties of ZnO nanowires (ZnO-NWs) that had been treated with Eu by thermal diffusion. The O K- and Eu L(3)-edge XANES and EXAFS spectra at the Zn K- and Eu L(3)-edge verified the formation of Eu(2)O(3)-like layer on the surface of ZnO-NWs. X-ray diffraction, XANES and EXAFS measurements consistently suggest the lack of substitutional doping of Eu ions at the Zn ion sites in the interior of ZnO-NWs. The clear sharp and intense emission bands in the range 610-630 nm of Eu-treated ZnO-NWs originated from the intra-4f transition of Eu ions in the Eu(2)O(3)-like surface layer.
High Efficiency Silicon Solar Cells with Bilayer Passivation Structure
(2009)
Sun, W. C.
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Chang, W. L.
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Chen, C. H.
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Du, C. H.
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Wang, T. Y.
lThe effects of passivation on monocrystalline silicon solar cells were investigated. Al(2)O(3) and SiO(2) films, prepared by atomic layer deposition and thermal oxidation, respectively, were used as passivation layers. Passivation using a monolayer (SiO(2)) yielded a cell efficiency of 17.5%. However, the Al(2)O(3)/SiO(2) bilayer structure drastically increased cell efficiency to 20.1%. Quantum efficiency results revealed a significant improvement in the IR range, suggesting that bilayer passivation was effective on the back of a solar cell in providing a high energy conversion efficiency. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3194252] All rights reserved.