Critical electronic phenomena in liquid alloys with miscibility gap

研究了液态Bi-Ga合金在两液相分离临界点附近的传导电子行为。液态Bi-Ga合金的电阻率rho随温度T的降低而适度降低，远高于临界温度T_c。然而，随着T_c的接近，rho急剧减小，特别是在均质液体的过冷温度范围内，即在双节线以下的T范围内。这被认为反映了浓度波动的增长，直到两相分离开始。此外，需要注意的是，这种过冷的T范围在临界成分X_c处最小，在X_c附近较大。这表明两相分离的开始可能是由旋量分解引起的。在此基础上，研究了在火箭发射实现的微重力条件下液态Bi-Ga合金的rho。结果表明，在微重力条件下，冷却过程中rho的下降始于比双节点温度高15K的温度。这说明微重力条件能很好地抑制对流对浓度波动生长过程的影响，为研究两相分离的真实特征提供了适宜的实验环境。此外，还发现微重力条件下的过冷程度远远大于1g条件下的过冷程度。这也表明微重力条件是研究过冷或非平衡性质的有效条件。

Behaviors of conduction electrons were investigated near the critical point of two liquid phase separation in liquid Bi-Ga alloys. The resistivity, rho, of liquid Bi-Ga alloys decreases moderately with the decrease of temperature, T,far above the ctitical temperature, T_c. However, with the approach to T_c the rho decreases abruptly particularly in the supercooling temperature range of homogeneous liquid, that is in the T range below the binodal line. This is considered to reflect the growth of concentration fluctuations up to the onset of the two phase separations. In addition it is to be noted that the T range of this supercooling is minimum at the critical composition X_c and larger around X_c. This indicates that the onset of two phase separations may be initiated by the spinodal decomposition. Based on these experimental facts the rho of liquid Bi-Ga alloys were investigsated under the microgravity, which was realized by the launch of rocket. It was found that under the micrograviuty, the decrease of rho on cooling process begins at 15K higher temperature than the the binodal temperature. This indicates that the microgravity condition is very effective to surpress the convection effects on the growth process of concentration fluctuations and provides the appropriate experimental circumstances for the study of true feature of two liquid phase separations. In addition it was found that the degree of supercooling is far larger under microgravity than under 1 g condition. This also indicates that microgravity conditions are very effective to study the supercooling or non equilibrium properties.