Superconductivity in Ca-Cu-Si with AlB2-type structure

• Main Authors: wun jie, 何文傑
• Other Authors: none
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/99840577750212462953

碩士 === 國立中正大學 === 物理所 === 93 === We report the discovery of superconducting materials in Ca-Cu-Si with AlB2 -type structure. The results of magnetic susceptibility and electrical resistivity measurements on two phase Ca-Cu-Si samples with nominal compositions CaCu0.25Si1.75, CaCu0.33Si1.67 and CaCu0.25Si1.70 provide evidence for bulk superconductivity in a hexagonal AlB2-type majority fraction of the sample volume. Power x-ray diffraction patterns indicate that the minor impurity phase is the element Si which has no effect on the superconductivity. CaCuxSi2-x samples with excess Cu component (x ≧ 0.4) showed no evidence of superconductivity for T ≧1.8 K . Under the annealing conditions required for the fabrication of the AlB2-type superconductor, the best sample with the nominal composition CaCu0.25Si1.70 annealed for three days at 1000℃ exhibits the transition temperature TC~3.2 K, as determined by magnetic susceptibility and electrical resistivity measurement techniques.