Strong-Coupling of The Different Diameter Nano Pb Powders
碩士 === 國立中央大學 === 物理研究所 === 91 === In this thesis, we use thermal vaper to produce nano Pb powders. By changing Ar pressure and the electric current on the boat to produce different size of nano Pb powders. By the magnetic measure, the critical temperature of 13nm Pb is 7.10K and the critical magn...
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| Format: | Others |
| Language: | zh-TW |
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2003
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| Online Access: | http://ndltd.ncl.edu.tw/handle/24870730708867168292 |
| Summary: | 碩士 === 國立中央大學 === 物理研究所 === 91 === In this thesis, we use thermal vaper to produce nano Pb powders. By changing Ar pressure and the electric current on the boat to produce different size of nano Pb powders.
By the magnetic measure, the critical temperature of 13nm Pb is 7.10K and the critical magnetc field is 3.13 Tesla. The critical temperature of 9nm Pb is 7.09K and The critical magnetic field is 4.48 Tesla.We know the critical temperature is 7.19K and the critical magnetic field is 803 Oe. This means that the diameter of nano Pb powders are smaller the critical temperature is lower but the critical field is higher. It only a little part of applied magnetic field can affect the superconductivity, So it needs more magnetic field to destroy the superconducting state.
Bulk Pb is strong- coupling. To simulation every samples, the α value of bulk Pb is 2.13. The α value of 13nm Pb is 2.22. The α value of 9nm Pb is 2.44. The α value of 7.5nm Pb is 2.86. The α value of 6nm Pb is 3.03. So nano powders are smaller the intensity of superconducting coupling are stronger.
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