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学术讲座——“金属液体的复杂特征:高温核磁共振研究”
发布日期:2017-1-3 10:52:47 阅读次数:608

新金属材料国家重点实验室学术讲座

SKL-AMM Seminar

题目/Title   金属液体的复杂特征:高温核磁共振研究

日期/Date时间/Time: 10:00 – 11:00 am  20170103日(星期

报告地点/Location: 北京科技大学 主楼 353

报告人/Speaker: 吴跃 教授 E-mailyuewu@physics.unc.edu

报告人单位/Affiliation: Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599-3255, USA. 华中科技大学材料科学与工程学院

联系人/Contact 吕昭平 教授(电话:010-82375387E-mailluzp@ustb.edu.cn

 

报告摘要/Abstacts:

Liquids, even simple liquids, could exhibit intriguing phenomena. For instance, a liquid of the same composition could assume different phases and undergoes a first-order liquid-liquid transition (LLT). Although it is easy to understand the immiscibility of ice and water, it is thought provoking to envision two liquid phases of the same composition becoming immiscible and coexisting, as would expected under a conventional first order phase transition. Previous reports of LLT found the transition in the supercooled liquid region where the effect of crystallization cannot be ruled out. I will discuss our observation of a LLT in La-based bulk metallic glass system above its liquidus temperature. The evidence is obtained from high-temperature nuclear magnetic resonance (NMR) and molecular dynamic simulation which shows that bond-orientational order plays a critical role in such LLT instead of the conventional order parameter, namely, density. Strong short-range orders and cooperativity are crucial for such LLT1. However, as will be discussed, we are still far from understanding the emergent phenomena arising from the complexity of liquids including their thermodynamics, dynamics, and structures. Some examples from high temperature NMR studies of molten alloys will be discussed.

[1] W. Xu et al. Evidence of liquid-liquid transition in glass-forming La50Al35Ni15 melt above liquidus temperature. Nature Communications 6, 7696 (2015).

 

报告人简介/Brief introduction of speaker:

Description: wu_yue教授,195911月生。于1978年考入北京大学,1979入比利时鲁汶大学物理系学,于1983得学士学位。之后继续汶大学物理系从事固体物理研究,Andre Stesmans教授,于198712博士学位。1988年至1991年在美国加州大学伯克利分校化学系从事固体核磁共振博士后研究,Alex Pines教授。1991至今在美国北卡大学(教堂山)物理天文系任教,现为美国北卡大学讲习教授(Kenan Distinguished Professor),中科技大学千人划特聘教授(B),美国物理学会理事(APS Fellow)。主要利用核磁共振方法从事米材料,金属玻璃,凝聚物理的研究先后发表了100余篇论文,其中3篇《Nature》文章、3篇《Science》文章、8篇《Physical Review Letters》文章、6篇《Journal of the American Chemical Society》文章,SCI总引用次数达3400余次。

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