Contact

Dr. Robert Möckel
Division of Analytics

Phone: +49 351 260 - 4444

Anne Rahfeld
Division of Analytics

Phone: +49 351 260 - 4484

Powder X-Ray Diffraction (P-XRD)

The Helmholtz Institute Freiberg for Resource Technology uses the Powder X-Ray Diffraction (P-XRD) complimentary to the Mineral Liberation Analysis (MLA) for the mineralogical phase analysis of rocks and synthetic mixtures that result from processing or recycling. Such analyses are needed not only for the exploration of new deposits, but also for the characterization of technological processes. Qualitative as well as quantitative data analyses are possible, depending on sample amount and preparation.


Equipment Features

  • Type: X-ray diffractometer PANalytical Empyrean, radius 240mm
  • X-ray source: Co
  • Automatic divergence aperture
  • 2 detectors: one proportional counter with monochromator and a PIXcel 3-D Medipix 1x1 semiconductor detector (with Fe-filter)
  • Sample changer for up to 45 samples

Key Features

  • Complementary to the MLA-method for phase determination and quantification
  • Quantitative phase determination by applying the Rietveld analysis using the open source software Profex/ BGMN

Sample Requirements

  • Quantitative analysis: sample quantities between approximately 2 to 3g and a grain size between 2 and 6µm (sample preparation maybe carried out at our institute)
  • Qualitative phase/ mineral analysis: requires a single grain only
  • Samples should be crystalline

Restrictions

  • A quantitative determination only works as long as structures are known
  • Detection limits are phase and compound dependent
Panalytical Empyrean: 1 Probenwechsler, 2 Probe, 3 Röntgenröhre, 4 Primäre Optik, 5 Sekundäre Optik und Detektoren
Panalytical Empyrean: 1 Sample changer, 2 Sample, 3 X-ray source, 4 Primary optics, 5 Secondary optics and detectors, Photo: HZDR / Robert Möckel
Probe für die Pulver-Röntgendiffraktometrie
Powder X-ray diffraction sample, Foto: HZDR / Robert Möckel

How does it work?

A primary, monochromatic X-ray hits a flat surface of a sample made of crystalline powder. The X-ray is scattered by the atoms in the crystals. Since the atoms are arranged in a very regular manner the scattered X-rays will be extinguished or enhanced in a similar regular manner. The resulting angle dependent diffractogram follows Bragg’s law and is characteristic for every different phase.

The Rietveld method is used for the quantification of phases in mixtures. This method compares theoretical single-phase diffractograms with the current measured data. Additionally it is possible to take several effects like microabsorption, preferred orientation into account. The result is the proportion of the phases in the analyzed mixture.