What is X-ray Powder Diffraction (XRD)

X-ray powder diffraction (XRD) is a rapid analytical technique primarily used for phase identification of a crystalline material and can provide information on unit cell dimensions. The analyzed material is finely ground, homogenized, and average bulk composition is determined.

Applications

X-ray powder diffraction is most widely used for the identification of unknown crystalline materials (e.g. minerals, inorganic compounds). Determination of unknown solids is critical to studies in geology, environmental science, material science, engineering and biology.

Other applications include:

• characterization of crystalline materials
• identification of fine-grained minerals such as clays and mixed layer clays that are difficult to determine optically
• determination of unit cell dimensions
• measurement of sample purity

With specialized techniques, XRD can be used to:

• determine crystal structures using Rietveld refinement
• determine of modal amounts of minerals (quantitative analysis)
• characterize thin films samples by:make textural measurements, such as the orientation of grains, in a polycrystalline sample
  • determining lattice mismatch between film and substrate and to inferring stress and strain
  • determining dislocation density and quality of the film by rocking curve measurements
  • measuring superlattices in multilayered epitaxial structures
  • determining the thickness, roughness and density of the film using glancing incidence X-ray reflectivity measurements

Strengths and Limitations of X-ray Powder Diffraction (XRD)?

Strengths

• Powerful and rapid (< 20 min) technique for identification of an unknown mineral
• In most cases, it provides an unambiguous mineral determination
• Minimal sample preparation is required
• XRD units are widely available
• Data interpretation is relatively straight forward
  

Limitations

• Homogeneous and single phase material is best for identification of an unknown
• Must have access to a standard reference file of inorganic compounds (d-spacings, hkls)
• Requires tenths of a gram of material which must be ground into a powder
• For mixed materials, detection limit is ~ 2% of sample
• For unit cell determinations, indexing of patterns for non-isometric crystal systems is complicated
• Peak overlay may occur and worsens for high angle 'reflections'

Contact

Ngo Hoang Long                       

Email: This email address is being protected from spambots. You need JavaScript enabled to view it. ĐT: 0937725075      

        Nguyen Ho Thuy Linh               

        Email: This email address is being protected from spambots. You need JavaScript enabled to view it. ĐT:0978375457