| Summary: | 碩士 === 國立臺灣大學 === 化學工程學研究所 === 87 === The object of this study is to improve the superconducting properties of the MTG 123 bulk. We found that the increasing dose of Nd422 could improve the Tc of Nd123 powder. The influence of oxygen partial pressure on Tc is large when the percentage of Nd422 in Nd123 is small. When the percentage of Nd422 is higher, the effect of pressure could be neglect. To the MTG Nd/Au bulk, the superconducting properties are very sensitive to oxygen partial pressure. First, the vacuum MTG process adopting 1 torr oxygen partial pressure could produce the bulk with higher Tc. Second, the low pressure heat treatment could really improve the superconducting properties.
The reaction between Y123 and Nd422 produce Nd123 and Y211. For better crystal quality, the melting temperature of Nd123 has to be viewed as peritectic point in the Y123/Nd422 MTG process. The vacuum MTG process can also result in better superconducting properties. The Tc of samples produced under normal pressure could be enhanced by low pressure heat treatment.
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