X-ray Diffraction (XRD)
- Practical Electron Microscopy and Database -
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Powder X-ray diffraction is a standard method of identifying crystal structures.

Mean-square atomic displacement <u2> values can be experimentally obtained from various measurements, such as thermal expansion, thermal conductivity, extended x-ray absorption fine structure (EXAFS) and the widths of the x-ray or neutron diffraction peaks.

High-resolution powder XRD data can be collected using a synchrotron radiation source (e.g. λ = 0.41222 Å).

Note that the RDF analysis is important for the study of non-crystalline solids. The RDFs can be experimentally measured after Fourier transformation of neutron or electron diffraction or X-ray diffraction (XRD) data.

Table 2858. Comparison between single crystal and powder X-ray diffractions.

  Single crystal X-ray diffraction Powder X-ray diffraction
Specimen Probes a single crystal in the specimen Probes the bulk specimen
Drawback Relies on the presence of single crystals so that these might not be representative of the specimen as a whole and it is not so uncommon to choose the nicest looking crystals in the specimen and later find out they are only a minor phase in the specimen. [1]  
     
     

 

 

 

[1] Jiri Cejka, Herman van Bekkum, A. Corma, F. Schueth, Introduction to Zeolite Molecular Sieves, 2007.

 

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