碳含量对Y-Ni-B-C超导相的形成与临界温度的影响

EFFECTS OF CARBON CONTENT ON THE FORMATION AND CRITICAL TEMPERATURE OF Y Ni B C SUPERCONDUCTOR

报道ＴｈＣｒ２Ｓｉ２ 型结构的四元金属间化合物Ｙ２Ｎｉ２Ｂ２Ｃｘ 的形成与超导电性．当碳配比含量ｘ ＝ ０－９ —１－２ 时，电弧熔炼的合金结晶为较好的ＹＮｉ２Ｂ２Ｃ 单相．当ｘ ＜ ０－８ 或ｘ ＞ １－２ 时，合金中虽仍以ＹＮｉ２Ｂ２Ｃ 为主相，但杂相明显增加．超导转变温度Ｔｃ 随碳含量增加明显分为两个台阶．ｘ ≤０－８ 时，Ｔｃ 约为１２－５ Ｋ；ｘ ≥０－９ 时，Ｔｃ 约为１５ Ｋ．

In this paper,we report the formation and superconductivity of quaternary intermetallic system YNi\-2B\-2C\- x with ThCr\-2Si\-2\|type structure.Samples prepared by arc\|melting crystallize in single phase of the composition of YNi\-2B\-2C\- x when x =0.9—1.2 while the secondary unknown phases increase obviously when x <0.8 or x >1.2.Superconducting\|transition temperature T c determined by the temperature dependence of magnetization displays two steps with increasing carbon concentration: T c≈12.5?K for x ≤0.8, T c≈15?K for x ≥0.9.