【摘要】 对晶体生长机制、动力学与微结构衍化的认识是实现纳米材料的尺寸和形貌可控制备的基础.以表面溶解沉积为特征的奥斯特瓦尔德熟化(OR)理论常用来解释传统的晶体生长过程.在该生长模式下,纳米晶体的生长呈现出小颗粒溶解而大颗粒逐渐长大的特征.在纳米材料体系,近来还发现了一种重要的新的晶体生长模式——"取向接合(OA)"机制,在该机制下,两个晶格取向一致的初级纳米颗粒可通过直接接合和结构调整,从而长成一个新的晶体.这一机制已被证实在许多纳米材料体系中广泛存在,并对所合成的纳米材料的形貌、微结构具有非常显著的影响,在构筑新型纳米结构方面具有潜在的优势.本文我们首先回顾了OA生长机制的认识历程和这一机制对材料科学的重大意义;进而,基于我们的研究工作系统介绍了OA生长动力学模型的建立与发展,进一步阐述了这一机制的微观过程及其对材料内部缺陷的特殊影响,深入地分析和讨论了表面包裹的强弱、表面作用的性质对OR机制和OA机制的抑制和调控作用;基于上述表面包裹可调控纳米材料的生长机制的认识,我们结合近期研究结果,从动力学角度分析了量子点的生长机制与其发光特性的内在关联,阐明了表面包裹调控量子点的发光性质的本质原因,为制备不同发光特征的量子点及理解其发光性质衍化规律提供了重要的理论指引.更多还原

【Abstract】 In-depth understandings of crystal growth mechanisms and kinetics provide guidance to tune the crystal growth and thus to achieve new types of nanostructures and new material properties.The common mechanisms to describe crystal growth is based on the Ostwald ripening (OR) theory and the newly discovered oriented attachment (OA) mechanism.The OR kinetics are characterized by the growth of larger particles at the expense of smaller particles.In OA mechanism,two common crystallographically oriented nanoparticles combine together to form a larger one.Recently,increasing attention is being paid to the role of OA in the formation of specific microstructure or self-assembly of nanomaterials.However,the majority of research is restricted to the investigation of the growth process itself rather than to get comprehensive insights of the kinetics and the underlying mechanism in particular.In this context,we review the progress of the OA mechanism and its important significance on materials science.Progress on the OA kinetic models was systematically summarized,showing the kinetic rules of size,morphology,and lattice structure of nanocrystals in OA or complexed OR+OA mechanism.The surface adsorption were proved to be an effective factor for arresting the OR process and facilitating the exclusive OA growth stage.The conrol mechanism of surface ligand on OR and OA were anaylzed thoroughly.Based on the above knowledge,attempts will be made to shed light on the relationship between the photoluminescence (PL) evolution rule of nanocrystal and the growth mechanism/kinetics of nanocrystals.We anticipate this work could provide the fundamental understanding for introducing the surface adsorption to tune the crystals growth of semiconductor nanocrystals,thus to tailor and achieve preparing QDs with desired PL properties.更多还原