纳米技术-课件-11_nanomaterials

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11.2 Size dependent materials properties
1. Size dependent optical properties
It is not a magic, but NANO play a trick
The effects on light emerging from a small object: comparison on a standard transparent materials´with a positive refractive index with that of one with a negative refractive index. It can be seen that the 2nd one produces an image of the object.
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11.3 Produce nano-particles: wet chemistry
Review: top-down vs. bottom-up process
Wet chemistry: Sol-gel process & reduction in solution
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11.1 Vision of nano-materials
Novel electronic and photonic properties Surface properties Magnetic properties Light weight Superior mechanic properties
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Ch. 11: Nano-materials
Points of interests (functions – smart materials) Self-heating structures Recognition and separation Catalysts Encapsulation …… Keys: Synthesis and reconfiguration of any materials at nano-scale
Strength e.g., property changes of Cu-based materials
………
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11.2 Size dependent materials properties
1. Size dependent optical properties
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11.2 Size dependent materials properties
3. Size dependent Chemical reactions Catalytic activity of Au cluster on TiO2
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Different sizes of semiconductor particles
- Shine (excite) with the same light source, but eventually show with different colour - Size variation 1-10 nm, so decreased carrier confinement shifts results in a reduced transition energy (red shift)
1. Sol-gel process / A & D
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11.3 Produce nano-particles: wet chemistry
2. Reductions in solution / What it is ? The way to produce metal nano-particles
Ch. 11: Nano-materials
Nano-scaled science and engineering most likely will produce the strategic breakthroughs of tomorrow. Our ability to work at the molecular level, atom by atom, to create something new, something we can manufacture from the “bottom up”, opens up huge vistas fro many of us … . This technology maybe the key that turns the dream of space exportation into reality. - David Swain, Senior VP of Engineering & Technology, Boring
11.3 Produce nano-particles: wet chemistry
1. Sol-gel process / What it is ?
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11.3 Produce nano-particles: wet chemistry
1. Sol-gel process / How it processes ?
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11.4 Produce nano-particles: spray pyrolysis
1. Spray pyrolysis / what & why
Nano-particles
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11.4 Produce nano-particles: spray pyrolysis
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11.5 Nano-composites
Definition
Nano-composites: Heterogeneous nanostructure, i.e., the material is not the same physically throughout its bulk
2. Reductions in solution / Applications Ni nano-particles for MLCC
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11.3 Produce nano-particles: wet chemistry
2. Reductions in solution / Applications Perovskite nano-particles
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11.2 Size dependent materials properties
2. Size dependent melting point
Melting point of Gold Tm = 1064 °C
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11.3 Produce nano-particles: wet chemistry
1. Sol-gel process / Applications
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11.3 Produce nano-particles: wet chemistry
- high hardness - high strength - high elasticity
Theoretical limit
Nano-materials
Hardness
Cu-Cr slice Cu-Nb wire systemsCu-Ag wire Reduce the size Present engineering materials
Features
Random shape Random size Broad size distibution Heterogeneous nucleation Additive (dispersant, complex agent)
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11.3 Produce nano-particles: wet chemistry
2. Spray pyrolysis process
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11.4 Produce nano-particles: spray pyrolysis
3. Application examples / NiO nanoparticles
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Ch. 11: Nano-materials
Points of interests (natural properties) Size-dependent properties Materials assembled by nano-particles Homogeneity and stability of nano-scaled materials Nanocomposites Keys: Synthesis and reconfiguration of any materials at nano-scales
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11.2 Size dependent materials properties