Materials Characterization

X-ray diffractometer

X-ray diffractometry is used for the determination of the crystallographic structure of thin films, powders and bulk materials. At the department, two diffractometers of type Bruker AXS D8 Advance are available. These diffractometers consist of a source of radiation (copper X-ray tubes), monochromators, various slits and detectors. During the measurement the sample is irradiated with monochromatic X-rays and the diffraction at the crystal lattice is investigated. By scanning a pre-defined range of diffraction angles maxima in the reflected X-ray intensity can be determined being characteristic for each crystalline material. This consequently enables the determination of the phase composition of solid samples. The detectors available at the department are energy-dispersive which results in an excellent signal-to-noise ratio, especially for steel samples, which tend to fluoresce under copper radiation. A Eulerian cradle allows to tilt the investigated sample thus making stress and texture analyses feasible. A high-temperature chamber (Anton Paar 1200 N) provides the possibility to heat samples up to 1200 °C in vacuum, air and oxidizing atmospheres enabling the investigation of phase transformations and chemical reactions.

 

Technical data:

  • Measurement geometry: Bragg-Brentano, parallel beam, gracing incidence, transmission, reflection
  • Radiation: copper K-alpha, line and point focus
  • Detectors: scintillation counter, energy dispersive detectors (0D and 1D mode)
  • Sample holder: nine position sample changer, Eulerian cradle, capillary holder and high-temperature chamber (up to 1200 °C)
  • Investigation atmospheres: vacuum, air and oxidative
  • Software: ICDD pdf-database 2018 und EVA (phase analysis), TOPAS (quantitative determination of phase compositions, Rietveld), TEXTURE (texture determination), LEPTOS (calculation of residual stresses)