纳米材料5课件.ppt

(2)NANOPARTICLE SYNTHESIS FROM GAS PHASE Towards size controlling: Important parameter: residence time (3)Hybrid method Aerosol Electrospray Ionization (ESI) Thermal spray Electrospray: Micron-sized droplets of a dilute solution 1mm droplet 1ppm solution 10nm particle Solvant evaporation, coulomb blockade, Multiple JET Size-selection: DMA(Differential mobile analyzer) Aerodynamic diameter: 5% distribution Mechanical grinding High energy shaker Ball milling Milling in cryogenic liquid Inert atmosphere to produce non-oxide materials Simple and inexpensive equipment Easily scaling to tonnage quantities Serious problems: contamination Suitable for producing amorphous or nanocrystalline alloy particles B Nanoparticle Assembly Self-assembly, self-organization, spontaneous ordering Pattern formation Nanopatterning of surfaces SPM-based manipulation approach Lithography through self-organization:let nature do the arranging of atoms. Technologically much simpler, Disadvantage:less control on structure size and shape. For nanotechnology applications where uniformity of structures has priority over special size and shape requirements, this concept promises to become a very cost-efficient route towards large-scale arrays of nanostructures. 自组装：复杂系统自发地组织，使组分单元形成特定的微相分离或表面分凝。 驱动力：分子或纳米粒子间的相互作用的竞争 亲水 versus 憎水 van der Waals, Coulombic, or hydrogen bonding Spontaneous formation of spatial, temporal or spatio-temporal patterns by self-organization of individual constituents is a common phenomenon in nature. It covers a wide range of length scales from atomic to cosmic dimensions. It can be found in open systems in the inanimate as well as in the animate world. Examples of macroscopic self-organized patterns A. Ripple pattern on wind-blown sand Examples of macroscopic self-organized patterns B. glacier morphology, Greenland, * 3. 纳米结构材料的合成与处理 A. Processes for producing nanoparticles Top Down Bottom