【作者】 周樨；

【导师】 郑兰荪； 谢兆雄；

【作者基本信息】 厦门大学 ， 无机化学， 2009， 博士

【摘要】 晶体的各向异性决定了晶体中不同的晶面或取向将会表现出不同的物理和化学性质。因此，具有特定形状和表面结构的的纳米晶体将表现出特定的物理和化学性质，在实际应用中发挥重要的作用。所以，如何实现对纳米晶体不同形状和裸露表面的的可控制备，是本论文的宗旨。本论文通过对研究体系（主要是金属氧化物）的晶体结构和晶体生长习性进行详细研究的前提下，利用晶体生长的各向异性，设计了一条在类似室温离子液体的溶液中通过对晶体表面能的调控实现纳米晶体形状和晶面可控生长的通用方法体系。即在由有机酸（如油酸）和有机碱（如已二胺）混合得到的类似于室温离子液体的特殊溶液中（R-COOH+R-NH₂（?）R-COO^-+R-NH₃⁺），通过其中大量的阴阳离子（酸根阴离子和铵根阳离子）与金属氧化物纳米晶体的极性晶面之间较强的静电吸附作用，有效地降低极性晶面表面的表面能，改变晶体各晶面间表面能高低的相对顺序，从而使通常难以裸露的极性晶面得以稳定并裸露出来，改变晶体的最终形状。利用该方法我们实现了各种不同类型金属氧化物纳米材料的形状控制合成：（1）通过在油酸和有机胺的混合溶液中，即存在大量酸根负离子和胺正离子的环境中，热分解醋酸锌，首次成功得到了全部以极性晶面（0001）和{10-11}作为裸露晶面的发光材料ZnO微／纳米六棱锥结构。ZnO六棱锥结构的合成，不仅进一步丰富了ZnO纳米家族，同时{10-11}极性晶面这一非常规晶面的裸露，为我们进一步开发与该晶面相关的新的性质和应用提供了基础。（2）进一步我们采用室温阴极荧光（CL）技术，直接研究了ZnO六棱锥不同晶面{10-11}、（000-1）和{10-10}的荧光性质，得到了与晶面相关的绿带荧光发射。通过对不同晶面表面原子结构的研究，我们认为ZnO微-纳米晶体的绿带发射主要来源于ZnO微-纳米晶体表面及表面附近的缺陷。（3）进一步我们将体系拓展到ZnO基稀磁半导体的晶面可控合成，首次合成了由极性晶面{10-11}和（000-1）裸露的Zn_1-xCo_xO和Zn_1-xMn_xO六棱锥状纳米晶体；并表征了稀磁半导体Zn_1-xCo_xO和Zn_1-xMn_xO的磁性。磁性分析表明这两种稀磁半导体在高温时表现为反铁磁性，而低温时表现为铁磁性。（4）此外，我们还将该方法拓展到熔盐型金属氧化物CoO、MnO体系，首次成功合成了完全由极性晶面{111}裸露的CoO、MnO八面体纳米晶体。值得注意的是，尺寸和形貌均一的MnO八面体纳米晶体自组装形成了三维超晶格结构。我们对其可能的形成机理也进行了探讨。此外，我们还与美国的科研团队合作，开展了将纳米材料应用到生物医学体系的探索，研究了表面增强拉曼（SERS）纳米生物传感器的设计合成及应用：主要基于长程等离子共振耦合效应和生物共轭的金纳米粒子，设计了表面增强拉曼纳米生物传感器，用于进行DNA等生物分子的检测。该传感器具有比传统的生物传感器更高的灵敏度和更好的选择性。更多还原

【Abstract】 Anisotropy is a basic property of single crystals,and the various facets ordirections in a crystal may exhibit different physical and chemical properties.Thus,surface architecture-controlled nanostructures are desirable for many applications.Forthis purpose,the controllable preparation of micro/nanocrystals with different shapesand exposed surfaces is very important and challenging.In this dissertation,using a mixture of fatty acid（such as oleic acid（OA））andorganic amine（such as ethylenediamine）as the solvent,which can be thought as onekind of ionic liquid（R-COOH + R-NH₂（?）R-COO^-+ R-NH₃⁺）as the growthenvironment,we designed a general route for the controllable preparation ofnanocrystals with different shapes and exposed surfaces.The key strategy is to varythe surface energy of the polar surfaces by strong electrostatic interactions betweenthe ions of the ionic liquid and the polar surfaces.With this concept,we successfullyachieved the controlling of exposed surfaces and morphologies of a wide range ofmetal oxide nanomaterials:（1）Using the mixture of fatty acid（such as oleic acid（OA））and organic amine（such as ethylenediamine）as the solvent,we have demonstrated a thermaldecomposition synthesis of ZnO hexagonal micro-pyramids,whosesurfaces are enclosed by polarized（000-1）and {101-1} planes.The newmorphology of ZnO hexagonal micro-pyramids not only enriches the ZnOnano-family,the abnormal {10-11 } facets may also provide new opticalproperties and applications.（2）We studied green emission of ZnO micro-pyramids by directly investigatingthe luminescence from the different crystal surfaces of ZnOmicrocrystallites by means of room temperature cathodoluminescence（CL）.The relative strength of the green emission was found to be stronglydependent on the crystal surfaces.By discussing the atom structures of different crystal surfaces,it is concluded that the green emission mostlycomes from the defects on/near the surfaces.（3）We further extend this method to the morphology-controlled synthesis ofdiluted magnetic semiconductors and achieved Zn_1-xCo_xO and Zn_1-xMn_xO hexagonal micro-pyramids,whose surfaces are enclosed bypolarized（000-1）and {101-1} planes.The magnetic characterizationshows they are antiferromagnetic at high temperature but ferromagnetic atlow temperature.（4）Moreover,we successfully synthesized surface-controlled rock-type metaloxide nanocrystals with the same stratege:CoO and MnO octahedralnanocrystal with all exposed surfaces being polar {111} planes.It is notedthat the MnO octahedral nanocrystal assembled to three-dimensionalsuper-lattice structure.We also discussed the formation mechanism.At last,we studied the biomedical application of nanomaterials.Specifically,wehave developed a class of surface-enhanced Raman molecular beacons（SERSbeacons）with novel mechanisms for molecular recognition and signal amplification.The key strategy is based on the long-range plasmonic coupling and bioconjugatedgold nanoparticles.The long-range nature of plasmonic interactions should allow thedevelopment of SERS beacons to detect proteins,clustered receptors on cellmembranes,and intact viruses,based on the coupling of adjacent metallic NPs in ano-wash/single-step format.In comparison with fluorescence emission,SERS spectracontain narrow molecular signatures that are well suited for multiplexing andbackground subtraction.更多还原