Xu Wei, Sandor Magdalena T, Yu Yao, Ke Hai-Bo, Zhang Hua-Ping, Li Mao-Zhi, Wang Wei-Hua, Liu Lin, Wu Yue
School of Materials Science and Engineering, and State Key Laboratory of Material Processing and Die and Mould Technology, Huazhong University of Science and Technology, 430074 Wuhan, China.
Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, 430074 Wuhan, China.
Nat Commun. 2015 Jul 13;6:7696. doi: 10.1038/ncomms8696.
Liquid-liquid transition, a phase transition of one liquid phase to another with the same composition, provides a key opportunity for investigating the relationship between liquid structures and dynamics. Here we report experimental evidences of a liquid-liquid transition in glass-forming La50Al35Ni15 melt above its liquidus temperature by (27)Al nuclear magnetic resonance including the temperature dependence of cage volume fluctuations and atomic diffusion. The observed dependence of the incubation time on the degree of undercooling is consistent with a first-order phase transition. Simulation results indicate that such transition is accompanied by the change of bond-orientational order without noticeable change in density. The temperature dependence of atomic diffusion revealed by simulations is also in agreement with experiments. These observations indicate the need of two-order parameters in describing phase transitions of liquids.
液-液转变，即一种具有相同组成的液相到另一种液相的相变，为研究液体结构与动力学之间的关系提供了关键契机。在此，我们报告了通过（27）Al核磁共振在高于其液相线温度的玻璃形成La50Al35Ni15熔体中发生液-液转变的实验证据，包括笼体积涨落和原子扩散的温度依赖性。观察到的孕育时间对过冷度的依赖性与一级相变一致。模拟结果表明，这种转变伴随着键取向序的变化，而密度没有明显变化。模拟揭示的原子扩散的温度依赖性也与实验结果一致。这些观察结果表明，在描述液体的相变时需要两个序参量。
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