Preparation of Nanomaterials

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Preparation of Nanomaterials
2
Introduction

• In 1984, German scientist Gleiter et al.
  successfully prepared iron nanoparticles for the
  first time by inert gas agglomeration. For
  decades, research on the preparation and
  application of nanomaterials has yielded fruitful
  results. The basic constituent particles of
  nanomaterials are of the order of nanometers in
  size and are particles in the intersection of
  atomic clusters and macroscopic objects. The
  diameter of the nanoparticles is generally
  between 1 and 100 nm. There are many preparation
  methods for nanomaterials, including sol-gel
  method, thermal synthesis method, liquid-phase
  organic synthesis method, inert gas condensation
  method, reverse micelle method, severe plastic
  deformation method and the like.

3
Sol-gel method

• The sol-gel method is one of the most important
  chemical methods for material preparation. It
  provides a new way to synthesize inorganic
  ceramics, glass, and nanomaterials at normal
  temperature and pressure. The main step of
  preparing the nano material by the sol-gel method
  is to select the metal compound to be prepared,
  then dissolve the metal compound in a suitable
  solvent and solidify it by a sol-gel process, and
  finally obtain a nanoparticle by low temperature
  treatment.

4
Thermal synthesis method

• The preparation of nanomaterials by thermal
  synthesis refers to the synthesis of
  nanomaterials in an aqueous solution under high
  temperature and high pressure, followed by
  separation and subsequent treatment to obtain
  nanoparticles. Thermal synthesis can produce
  products including metals, oxides, and composite
  oxides. This method is mainly used in the
  preparation of ceramic oxide materials.

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Liquid-phase organic synthesis method

• The liquid-phase organic synthesis mainly uses
  metals, organic compounds and some inorganic
  compounds having special properties which are
  stable in an organic solvent as a reactive raw
  material. These reactants are usually very
  sensitive to water and can not be stably present
  in aqueous solvents, so the most commonly used
  reaction method is to perform reflux in an
  organic solvent to prepare nanomaterials.

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Inert gas condensation method

• The inert gas condensation method is one of the
  main methods for preparing nano powders. The main
  process of the inert gas condensation method is
  to fill low-pressure inert gas in the vacuum
  evaporation chamber, and then vaporize the raw
  material to form a plasma by vacuum evaporation,
  heating, high-frequency induction or the like.
  The material gas molecules collide with the inert
  gas molecules to lose energy, and agglomerate to
  form nano-sized clusters. The inert gas
  condensation method has a fast reaction speed, no
  other impurities in the process, and the prepared
  nano material has high purity. However, this
  method has higher requirements for reaction
  technology and equipment.

7
Reverse micelle method

• The micro-droplet of reverse micelle in the
  water-in-oil microemulsion is a special
  nano-space, which can be used as a reaction field
  to exchange and react the reactants in different
  micelles to prepare nano-scale particles. In the
  preparation process, the reverse micelle is a
  tiny reaction field and can also be called a
  smart microreactor. When using reverse micelles
  for nanomaterial preparation, the reactants can
  be directly added or blended. Different addition
  methods correspond to different reaction
  mechanisms, but the results are the same, that
  is, highly dispersed and uniform nanoparticles
  can be prepared.

8
Severe plastic deformation method

• Severe plastic deformation method means that
  under the action of quasi-static pressure, the
  material undergoes severe plastic deformation to
  refine its size to the nanometer order. The bulk
  material is typically refined into a mixture of
  crystalline and amorphous materials under
  quasi-static pressure and then heat treated to
  form nanomaterials. The material prepared by the
  method has high purity and good controllability
  of particle size.

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Conclusion

• Nanomaterials have distinct properties that are
  different from bulk materials and individual
  moleculessmall size effects, surface and
  interface effects, quantum size effects, and
  macroscopic quantum orbital effects. Due to the
  special physical, mechanical, electrical,
  magnetic, optical and chemical properties of
  nanomaterials, they are of great value in the
  fields of electronics, optics, chemistry,
  ceramics, biology and medicine. Therefore, it is
  foreseeable that nanomaterials will become one of
  the pillars of the new round of industrial
  revolution in the 21st century.