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Nonclassical Nucleation

来源:合肥微尺度物质科学国家实验室    浏览次数:0


报告题目   Nonclassical Nucleation
报告人   Prof. Helmut Cölfen
报告人单位   Universität Konstanz
报告时间   2017-09-09   15:30
报告地点   合肥微尺度物质科学国家实验室九楼会议室(9004)
主办单位   合肥微尺度物质科学国家实验室、中国科学技术大学化学与材料科学学院
报告介绍
报告摘要:
In recent years, research on nucleation and crystallization has revealed alternative pathways to the classical ones known from the textbooks of crystallization. These so called nonclassical pathways allow for a better understanding of so far difficult to understand crystallization processes as observed for example in Biomineralization. In addition, they open up entirely new possibilities for the control of crystallization processes and therefore crystals, which would be impossible to synthesize by classical methods.
The presentation will focus on nonclassical nucleation processes for the example of CaCO3. It can be shown that so called prenucleation clusters of ca. 40 ion pairs in size exist in equilibrium with the ions and ion pairs. These clusters are highly dynamic polymers which constantly form and dissociate. Their formation is entropically driven by the release of hydration water. Increasing the overall ion concentration leads to a decrease in their dynamics and a phase transition in form of binodal demixing to nanodroplets. These coalesce and form larger droplets which solidify and form amorphous CaCO3, which finally crystallizes. This multi-step nucleation scenario is not only relevant for CaCO3, but also other minerals like calcium oxalates or phosphates and also organic molecules like amino acids. For the example of glutamic acid, it will be shown that classical layer by layer growth can be initiated by nanodroplets which attach to the crystal surface from the solution phase.

报告人简介:
  Helmut Cölfen 教授于1991年、1993年分获德国杜伊斯堡大学物理化学专业学士、博士学位;1993-1995年,英国诺丁汉大学,博士后;1995-2001年,德国马克斯普朗克研究所,副教授;1995-2010年,德国马克斯普朗克胶体与界面研究所研究组组长、资深研究员;2010年至今,任德国康斯坦茨大学化学系全职教授。 Cölfen教授是生物矿化领域的国际著名科学家,主要致力于研究材料的成核、结晶与性能的关系,在原子尺度上通过合理的自组装形成纳米结构,研究其在太阳能电池、催化剂、超级电容器、力学材料等领域的应用,并取得了许多令人瞩目的成绩。已在Science, Nature Materials, Nature Chemistry, Nature Communications, PNAS, Angew. Chem.Int. Ed., J. Am. Chem. Soc., Adv. Mater., Nano letters, ACS Nano, Physical Review Letters等国际高水平杂志上发表论文230余篇,SCI引用超过12,000多次。

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