X-ray diffraction

$X-ray diffraction$

X-Ray Diffraction

Support staff

The main objective of the department is the characterization of materials by means of various experimental X-ray diffraction devices, i.e. a fleet of ten diffractometers which are divided into six four-circle goniometers (two of which are at the exit of a rotating anode), three three-circle goniometers and a device for the orientation of single crystals by the Laue method in return. Four devices are prototypes developed internally in the department.

The most significant expertises are :

the determination of the stored energy at the grain scale or on components of identified textures in polycrystalline materials
measurements and analysis of global textures, macroscopic residual stresses on solid materials or thin films
refinement of structures from diffraction spectra (Rietveld)
characterizations under grazing incidence orientation of single crystals study of their disorientation after deformation.

The four prototype circles, unique in France, are installed on a 12 kw rotating anode, Co source with linear focus, 0.5*10 mm²:

Very high resolution parallel beam diffractometer. The analyses carried out concern mainly the evaluation of the energy stored in polycrystalline metallic materials, the analyses under grazing incidence in thin film materials.

Main features :

Motorized Bartels monochromator, Ge 220 or 440, 2 or 4 reflections
Motorized 3-axis sample positioning stages (5mm stroke, minimum pitch: 40 nm)
Detection set : linear detector (Δ2θ = 8.4*10-4°) or point detector with rear monochromator (Δ2θ = 5.0*10-3°)

Convergent beam diffractometer. Structure refinement by Rietveld analysis of spectra, determination of macroscopic residual stresses, crystallographic textures.

Main features :

Curved Si O2 monochromator 10.1, back focusing ;
Soller slits limiting the vertical divergence of the beam to 0.5°;
Sample positioning plates: 3 motorized axes. Stroke 5mm, minimum pitch: 40 nm;
Detection assembly: motorized curved linear detector, (120° aperture, Δ2θ = 1.5*10-2°) or point detector (Δ2θ = 1.0*10-2°).

Diffractometer dedicated to the analysis of crystallographic textures on metallic materials, Co source with point focus, detection scale with energy discrimination.

Main features :

Graphite monochromator 00.2
Detection set : scintillator, energy discrimination;
Different software for the determination of the orientation distribution function (ODF).
Collimators whose diameter is adjustable according to the grain size of the analyzed material

Diffractometer (Equinox 5000, INEL) dedicated to structure refinement by Rietveld analysis of spectra, crystallographic texture analysis on metallic materials, grazing incidence measurements, Cu source.

Main features :

90° curved linear detector (Δ2θ ˜ 0.012°), motorized
Different software to determine the orientation distribution function (ODF)
Two possible configurations : linear beam with fine focus or monochromatic point beam (Ge 111 or graphite 00.2)

Very high resolution diffractometer. The analyses carried out mainly concern the evaluation of the stored energy for large grain samples or single crystals, Guinier device, achromatic assembly.

Main features :

Ge 440 monochromator under primary vacuum
3 axis stage for sample positioning
Detection assembly : linear detector (Δ2θ = 8.4*10-4°)
Diffracted beam path under primary vacuum

Three-circle diffractometers:

Three devices (INEL) dedicated to the refinement of structures by Rietveld analysis of spectra.

Their main characteristics are :

Fine linear focus, monochromatic, Co, Cu type
Curved linear detectors (110°/120°, θ/2θ, Δ2θ 0.03°)
Single crystal powder diagram: (Gandolfi camera)
Temperature measurements (T max = 1200° c) under controlled atmosphere (Anton Paar furnace)

Nomadic system (XSOLO, INEL) for determining macroscopic residual stresses, Cu 4w source:

The originality of this system lies in the transportable aspect of the device, the measurement made without contact with the part and the data processing based on a Rietveld analysis.

Main characteristics :

4W Cu source ;
2D CCD detector cooled by Peltier effect;
90°<2θ<170° detection
Angular sensor : Ψ/2θ
Working distance: 22 mm

Single crystal orientation device, Laue in return :

Main features:

Point source W
Orientations of the crystalline symmetry
Analysis of samples of all sizes and geometries