Study of intermetallic compounds isostructural to MgB2

R. L. Meng, B. Lorenz, J. Cmaidalka, Y. S. Wang, Y. Y. Sun, J. Lenzi, J. K. Meen, Y. Y. Xue, C. W. Chu

研究成果: Conference article同行評審

13 引文 斯高帕斯(Scopus)

摘要

The small intergrain effect of MgB2 on supercurrent makes it one of the most promising candidates for superconducting conductors due to its easier processing and the associated lower manufacturing cost. Unfortunately, the superconducting transition temperature Tc is only 40 K. However, band-structure calculations predict that a higher Tc than that of MgB2 is possible for isostructural and isovalent intermetallic compounds with greater lattice parameters or greater unit cell volumes. The prediction appears to be consistent with the negative pressure effect on Tc observed. The substitution of the larger Ca-ions for the smaller Mg-ions has thus been suggested to raise Tc, but not yet realized. Alternatively, we have synthesized and studied a series of binary and pseudobinary intermetallic compounds, AGa2, AGa2-xSix, and AAl2-xSix, where A = Ca, Sr, or Ba, which are isostructural to MgB2 and have greater lattice parameters than MgB2. In spite of the greater lattice parameters, AGa2 are not superconducting. However, all pseudobinary compounds AGa2-xSi2 and AAl2-xSi2 for 0.6 < x < 1.5 are superconducting. Superconductivity is reported for the first time in SrAlSi, with Tc of 5.1 K. Although Tc varies with x in a similar fashion for all members of the series, no specific correlation between Tc and lattice parameters or ionic mass is observed. The maximum Tc of these compound series with different A's varies between 5.5 and 7.8 K, much lower than that of MgB2. The results strongly suggest the unique role of B in the superconductivity of C32 intermetallic compounds. They also demonstrate that factors additional to the lattice parameters and densities of states must play an important role, and that the rigid-band model is not sufficient to account for the observations.

原文English
頁(從 - 到)3042-3046
頁數5
期刊IEEE Transactions on Applied Superconductivity
13
發行號2 III
DOIs
出版狀態Published - 2003 6月
事件2002 Applied Superconductivity Conference - Houston, TX, United States
持續時間: 2002 8月 42002 8月 9

All Science Journal Classification (ASJC) codes

  • 電子、光磁材料
  • 凝聚態物理學
  • 電氣與電子工程

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