Energy-Dispersive Neutron-Transmission Diffraction (EDNTD)(An alternative for steady state source)

Pavol Mikula, NPI v.v.i. Řež

Energy-Dispersive Neutron-Transmission Diffraction

2dhklsin hkl=

hkl==2dhklDiffraction edge I() modulation

Instrumental resolutiond/d=5.7x10-4

The resolution (the sensitivity to the Bragg edge shift due to the strain) depends on several parameters:

•Thickness of the bent crystal monochromator (smaller thickness of the crystal, the resolution is higher, however, the luminosity of the instrument is lower)

•Take-off angle of the monochromator (the larger take off angle, the resolution is higher)

•The width of the slit in front of the sample

•Spatial resolution of the 1d- position sensitive detector and/or the distance between the sample and the detector

Sample thickness dependence of Ao

FWHM=5.7x10-4 rad

FWHM=12.5x10-4 rad

EDNTD examplesBragg diffraction edge of a 8 mm thick sample.

Energy-Dispersive Neutron-Transmission Diffractionlow-carbon steel 0.22% C, 0.64% Mn, 0.41% Si, 0.035% P, 0.04% S (in wt.%) Fe (321) diffraction edges

Comparison of the EDNTD with the conventional Bragg-diffraction-angle analysis technique

46.4 46.8 47.2 47.6 48.0

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5% strain

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110 reflection