- What is a PDF
- PDF on powder diffraction
- PDF on structure analysis
- PDF for SCD
- PDF in your lab
Incoatec Microfocus Source IμS combined with a mardtb and imaging plate detector mar345. The hot-air blower is pointing to the sample.
Diffraction pattern of copper phthalocyanine with the phase transition at approximately 300 °C
PDF analysis in the home lab - not just for experts
Atomic Pair Distribution Function (PDF) analysis is a powerful technique that makes use of total scattering data - Bragg peaks and diffuse scattering. It is useful for crystalline, nano-crystalline materials as well as liquids and glasses. PDF provides local structure information and can gives insights where classic diffraction can´t.
PDF analysis are relevant for
- Crystalline materials with unexpected structure or properties
- Disordered materials where physical properties are often dictated by defects or domains of local structure
- Nanomaterials with poorly defined Bragg peaks and the long-range order is limited to a few nanometers
- Non-crystalline, amorphous materials and polymers
Radial atomic Pair Distribution Function gives the interatomic distance distribution, or the "probability" of finding atomic pairs of distance r apart. It is a real space function and gives information about the relation of the atoms to each other.
A PDF analysis gives you information about the peak positions, peak areas, peak widths and peak damping.
IµS-Mo setup for the measurements in transmission geometry
Book-painting with indicated colors and diffraction pattern of green and red colored regions
Microdiffraction on a mediaeval book-painting
The IµS with Mo-Kα radiation and a SMART 1000 CCD-detector were mounted on an optical bench to analyse pigments in a mediaeval book-painting. The chemical composition of the investigated region was analyzed with simultaneous XRF measurements. For each frame an exposure time of 30 seconds was sufficiant for a detailed data analysis of the pigments. With this setup it was possible to scan in an overnight measurement an area of several square millimeter with a resolution of 150 µm.
IµS-Cr mounted at a Bruker AXS GADDS system with VÅNTEC2000 detector
Profile across a 6 mm weld seam, measuring steps 1 mm
Measurement of residual stresses
The IµS with Cr-Kα radiation was mounted at a goniometer with 1D wire detector and with VÅNTEC2000 area detector respectively. Residual stresses on various iron-containing samples like welds, motor parts, or steel springs were measured using the sin²ψ-method. Using Cr-radiation has the advantages that no iron fluorescense is excited and the Fe (2 1 1) reflex is at 155°2θ. This reflex is very sensitive to strain in the sample.
IµS integrated in a Bruker AXS GADDS system
Pole figure of the YBCO (004) reflex (left) and BaHfO3 (110) reflex
PDF Measurements on D8 VENTURE with IµS
The D8 VENTURE is equipped with a Cu- and Mo IµS as well as a KAPPA4 goniometer and a PHOTON III detector. When working with the highly focused high-brilliance point-focus beams of the IµS only tiny sample amounts are required. The PHOTON III detector gives the highest sensitivity for weakest signals and hard radiation.
The entire data set of a ZrO2 powder was collected in 2 frames with a Mo-IµS DIAMOND. The measurement time was 5 minutes. ZrO2 exixts as 3 different polymorphs, each differs in catalytic activity and selectivity.
Incoatec Microfocus Source IμS in combination with a mardtb and an imaging plate detector mar345
Recorded frames of measured parts of sepia cuttlebone
Left: inorganic part of the cuttlebone
Right: organic layer of chitin
PDF analysis are also possible in your lab.
If you want to start using PDF and want to measure
- overnight: simply exchange your X-ray tube from Cu to Mo or Ag
- in a few hours: increase speed and performance with special dedicated optics and large 2D detectors
- in less than 1 hour: work with Bruker´s existing SCD instrument or add some components for extra intensity