Nano

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IGC (Induction-Generated Copper) Technique

• Uses radio frequency (RF) induction technique to rapidly heat metal, producing high vapor pressure and substantial evaporation rate
• Reactor is continuously supplied with cryogenic liquid to form nanoparticles through rapid condensation of supersaturated metal vapor

Condensation Region

• Features high temperature gradient: 2200 K at metallic surface to 77 K in cryogenic medium
• High temperature gradient enables rapid cooling of as-formed particles, limiting crystal growth
• Produces high rate of nucleation, favoring particle formation

Synthesis of Nanoparticles

• Liquid argon used to synthesize Al nanoparticles, preventing formation of aluminum nitrides
• Liquid nitrogen used to synthesize Cu and Fe nanopowders
• Technique yields Cu nanoparticles with:
  • Spherical shape
  • Size distribution following log-normal function
  • Peak size at 25 nm
• Aluminum nanoparticles also produced with:
  • Spherical shape
  • Size less than 70 nm

Dislocations

• Missing rows of atoms in a crystal are regions of high energy and stress due to disruption of the atomic bonds in the plane
• Dislocations provide a driving force to be annihilated at surfaces or grain boundaries to minimize the strain energy of the crystal
• The attractive force exerted by the surface on dislocations in the crystal is inversely proportional to the distance of separation
• This force becomes negligible for dislocations farther than a critical distance
• The attractive force can be large enough to result in annihilation of dislocations close to the surface or grain boundary
• Image force ($F_{image}$) is the force exerted by a virtual imaginary image dislocation on the dislocation defect in bulk

Nanomaterials Technology

Properties of Nanomaterials

• Nanomaterials exhibit novel and unique properties when approaching nanoscale dimensions
• Atomic arrangement and chemistry influence the properties of the material
• Engineering at the nano-level can bring about large changes in the properties of the products
• High defect concentration in nanomaterials results in novel optical, electrical, chemical, elastic, and mechanical properties

Microstructure and Defects in Polycrystalline Materials

• Grain size, distribution, and morphology influence the properties of a material
• The nature of grain boundaries and interphase interfaces affects the properties of a material
• Intragrain defects and composition profiles across grains and interfaces are important microstructural features
• Residual impurities from processing influence the properties of a material
• Grain boundaries are ubiquitous features of the microstructure in polycrystalline materials
• Grain boundaries and interfaces influence many mechanical, physical, and chemical properties
• Dislocations are common defects observed within metallic materials, responsible for plastic deformation and flow
• Dislocations can be trapped and pinned at grain boundaries, contributing to the strength of materials
• The size, shape, and orientation of grains and the nature of interfaces affect the mechanical and physical properties of materials significantly