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X-ray Diffraction (XRD)

Compared to other methods of analysis, X-ray diffraction technique (XRD) allows for rapid, non destructive characterization of crystalline materials without the need of extensively sample preparation. Identification is obtained by comparison of the diffraction pattern against a database maintained by the International Centre of Diffraction Data. It provides information on structures, phases, preferred crystal orientations and other structural parameters such as crystallite size, crystallinity, strain and crystal defects.

It is based on the elastic scattering of x-rays from structures having long range order. Atoms and molecules that compose substances are commonly arranged at a distance ranging from 0.1 to 0.5 nm. When irradiated with a parallel beam of monochromatic X-rays having a wavelength approximately equivalent to the inter-atomic or intermolecular distance, the atomic lattice of the sample operate as a tree dimensional grating and the X-rays are diffracted from the crystal lattice at specific angles according to the Bragg law.

If the incidence angle is restricted to low values, the X-ray penetration depth can be limited to few hundreds of Angstrom and thin films and layers characterization can be performed. The low angle makes increase the path length of the incident X-ray beam through the sample and the investigation became more surface sensitive reducing the substrate contribution. The incidence angle can also be varied in order to probe the penetration depth through the film.

The Italstructures APD2000 XRD instrument is equipped with optical modules that can be exchanged depending on the analysis requirements.

It is simple to switch between Bragg Brentano and parallel beam configuration, enabling analysis of powder, bulk, coatings and thin films.

Capabilities

  • Non-destructive analysis
  • Phase identification for a wide range of materials
  • Bulk and thin films (> 20 nm) analysis
  • Crystallite size determination for  polycrystalline films and materials
  • Strain analysis
  • Grade of crystallinity evaluation (percentage of material in crystalline form versus amorphous)
  • Lattice parameter determination

 Limitation

  • Amorphous and glassy materials can not be analyzed
  • X-ray beam size 2 x 8mm
  • Very poor lateral resolution
  • Detection limit greater than ≈ 1%
  • Quantitative analysis with reference materials

 Sample requirements and size

  • ambient condition for all analysis
  • negligible sample preparation
  • ≥ 5 x10mm minimum sample size