Electron microscopy
 
Different TEM Techniques for Crystalline Grains in Various Sizes
- Practical Electron Microscopy and Database -
- An Online Book -
Microanalysis | EM Book                                                                                   http://www.globalsino.com/EM/        

This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.
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In practice, the TEM techniques used for grain analysis can be different depending on the grain size in the materials:

        i) For TEM specimens with very small grain sizes (<10 nm), the material is in nanocrystalline phase. In such cases, we can have:
        i.a) No single grain extends through the thickness of the specimen because the specimen thickness is normally between 50 and 100 nm.
        i.b) The grains are distributed particles on a thin film (e.g. nano-materials on a carbon film in a Cu TEM grid).
In Case i.a), we can’t easily index an individual crystal pattern. Fortunately, in this case, we normally don’t need to know the orientation of a particular grain. Instead, we are more interested in the texture of the material. In Case i.b), we are able to index an individual crystal pattern.

        ii) For TEM specimens with grain sizes between 10 and 100 nm, NBD and CBED are useful because they provide us a small probe. However, most benefit of CBED originates from specimens which are thicker than 100 nm.

        iii) For TEM specimens with grain sizes between 100 and 1 µm, most electron diffraction techniques may be useful except EBSD.

        iv) For TEM specimens with grain sizes larger than 1 µm, all electron diffraction techniques may be useful.

 

 

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