The detailed analysis of newly found concentration fluctuations near the eutectic point in the homogeneous liquid phase of eutectic systems

本研究发现共晶体系的均相液相在共晶点附近存在浓度波动。本研究计划的目的是为这种浓度波动建立严格的证据，并提出详细的观点。在Spring-8上对液态深共晶体系Au-Ge进行的EXAFS实验显示了这种浓度波动存在的一些证据。对“深共晶体系”，即Au-Si、Au-Ge、Ag-Si、Ag-Ge体系的电阻率进行了精确测量，结果显示出较大的浓度波动，波动幅度达7 vol.%。对具有多共晶点的液体共晶体系进行了精确的电阻率测量，结果表明，在均匀液相中，每个共晶成分周围都有异常行为。共晶成分均相液相中的浓度波动可表现为微观的预凝固现象。这表明均相液体在共晶组分下的过冷倾向最小。这一观点不同于人们对共晶液体的普遍认识，它告诉我们共晶液体具有最大的过冷倾向和玻璃化能力。对一些共晶体系均相过冷现象的文献分析表明，在共晶组成中，均相液相的过冷倾向最小。因此，通过DSC实验研究了液态深共晶体系Au-Ge的过冷行为。当然，共晶成分的超冷倾向最小。这有力地支持了均匀液相中共晶组分周围存在浓度波动的理论。未来，详细的结构分析必须通过大规模的计算机模拟来完成。必须确认的是，在离子液体、水溶液等多种共晶液体中，均相共晶组分周围普遍存在浓度波动。少

The present investigator has found the existence of concentration fluctuations near the eutectic point in the homogeneous liquid phase of eutectic systems. The purposes of this research program are to establish the rigorous evidences for this concentration fluctuation and to present the detailed view about it. The EXAFS experiment in the Spring-8 for liquid deep eutectic system, Au-Ge, showed some evidence for the existence of such a concentration fluctuation. The precise measurements of electrical resistivity for "deep eutectic systems", Au-Si, Au-Ge, Ag-Si, Ag-Ge systems, showed the large concentration fluctuations, which amounts to 7 vol.%. The accurate electrical resistivity measurements for liquid "eutectic systems with multi eutectic points" showed an anomalous behavior around every eutectic composition in homogeneous liquid phases. The concentration fluctuation in the homogeneous liquid phase of eutectic composition may appear as the microscopic presolidification phenomena. This … More implies that the supercooling tendency of homogeneous liquids must be smallest at the eutectic composition. This proposal is different from the prevailing common sense about the eutectic liquids, which tells us that the eutectic liquid has the largest supercooling tendency and glass forming ability. The analysis of previous literatures about the homogeneous supercooling in some eutectic systems showed that the supercooling tendency of homogeneous liquid phase is smallest at the eutectic composition. Therefore, the supercooling behavior was investigated by the DSC experiments for liquid deep eutectic system, Au-Ge. Surely the supercoling tendency is smallest at the eutectic composition. This strongly supports the existence of concentration fluctuations around the eutectic composition in the homogeneous liquid phase. In future, the detailed structure analysis must be performed by the large scale computer simulations. It must be confirmed that the concentration fluctuations exist around the eutectic composition in the homogeneous liquid phase universally in various eutectic liquids of many kinds, such as ionic liquids, water solutions, etc. Less