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报告题目 |
Non Classical Nucleation and Crystallization |
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报告时间 |
2014年9月1日下午15 : 30 | |
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报告地点 |
合肥微尺度物质科学国家实验室一楼科技展厅 | |
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报告人 |
Prof. Dr. Helmut Cölfen, Department of Physical Chemistry, Universität Konstanz, Germany | |
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报告摘要： The description of nucleation has been dominated by the classical nucleation theory (CNT) for more than 80 years. However, significant problems exist for the understanding and description of real nucleation or crystallization events using CNT. Most problematic in CNT is certainly the assumption of bulk properties even for the smallest metastable clusters. Instead, it has turned out for CaCO3 and several other systems that nucleation can also follow an alternative pathway involving prenucleation clusters, which are thermodynamically stable with respect to the initial ions and are solutes containing some tens of ions. It turned out that for CaCO3, the prenucleation clusters can be understood as dynamic polymers and their formation is entropically driven by release of ion hydration water. Prenucleation clusters even form in undersaturated solution without driving force towards precipitation. The current knowledge about prenucleation clusters will be presented and discussed. However, even beyond the stage of nucleation, crystal growth does not necessarily proceed along the classical mechanism of the addition of atom/ion/molecule building units to the growth sites of a growing crystal. Instead, nanocrystals can self assemble via different mechanisms or crystallize from an amorphous precursor phase to form so called "Mesocrystals". This is an abbreviation for "Mesoscopically structured crystals" and involves the crystallographically aligned superstructure of nanoparticles as a kinetic intermediate. Potential fusion of the already crystallographically aligned nanoparticles after displacement of surface attached stabilizer molecules can lead to crystallographic fusion of the two aligned crystal faces better known as "Oriented Attachment". These processes are known as "Nonclassical Crystallization". Several of these nonclassical mechanisms will be presented and discussed. | ||
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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；2014年入选中国科学院外国专家特聘研究员计划。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，H index = 56。他还致力于纳米科学与纳米技术的产业化，获得了多项具有影响力的荣誉，曾入选汤姆孙路透“Top 100 chemists worldwide for the years 2000-2010”和世界排名机构Times High Education“Top Chemists of the past Decade”。Helmut Cölfen 教授被多个国际会议邀请做大会或邀请报告。曾获得“Dr. Hermann Schnell Award”,“Academy Award of the Berlin Brandenburg Academy of Sciences and Humanities”和ECIS Solvay Award of the European Colloid and InterfaceSociety等。 | ||
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参加者：所有感兴趣的老师和学生 | ||
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主办单位：化学与材料科学学院、微尺度、外事办 | ||