高压高温处理对A15Nb_3(Al,Ge)结构成分及其超导性能的影响

EFFECTS OF HIGH PRESSURE-HIGH TEMPERATURE TREATMENT ON THE STRUCTURE COMPOSITION AND SUPERCONDUCTIVITY OF Nb_3(Al, Ge)

在0—67kbar压力范围,对名义成分为Nb_3(Al_(1-x)Ge_x)的合金(x=0.20,O.23,0.25;含有Al5+σ相)进行了热处理。X射线分析表明:1)随着压力的升高,Al5相的晶胞参数a_0出现极大值;2)与Al5相结构成分密切相关的衍射峰(211),(210)的相对累积强度I^(211)/I^(210)随压力的变化与a_0的变化类似;3)Al5相结构成分随压力向着富Nb的方向移动。低温测试结果表明:随着压力的升高,试样的超导转变温度降低,转变宽度出现极大值。

Alloys of different nominal composition Nb3Al1-xGex (where x = 0.20, 0.23, 0.25 containing A15 + σ phases) have been heat-treated under high pressure up to 67kbar. With increasing treating pressure, 1) the lattice parameter of A15 phase as well as the I211/I210 of relative integral intensity of X-ray diffraction peak (211) and (210) of A15 phase having some concern with structure composition both exhibits a maximum, 2) the structure composition of A15 phase shifts toward the Nb-rich direction, 3) the superconducting transition temperature Tc decreases, while the width of superconducting transition temperature range shows a maximum. ......The results were discussed.