Deriving Quantitative Crystallographic Information from the Wavelength-Resolved Neutron Transmission Analysis Performed in Imaging Mode

Abstract

Current status of Bragg-edge/dip neutron transmission analysis/imaging methods is presented. The method can visualize real-space distributions of bulk crystallographic information in a crystalline material over a large area (~10 cm) with high spatial resolution (~100 µm). Furthermore, by using suitable spectrum analysis methods for wavelength-dependent neutron transmission data, quantitative visualization of the crystallographic information can be achieved. For example, crystallographic texture imaging, crystallite size imaging and crystalline phase imaging with texture/extinction corrections are carried out by the Rietveld-type (wide wavelength bandwidth) profile fitting analysis code, RITS (Rietveld Imaging of Transmission Spectra). By using the single Bragg-edge analysis mode of RITS, evaluations of crystal lattice plane spacing (d-spacing) relating to macro-strain and d-spacing distribution's FWHM (full width at half maximum) relating to micro-strain can be achieved. Macro-strain tomography is performed by a new conceptual CT (computed tomography) image reconstruction algorithm, the tensor CT method. Crystalline grains and their orientations are visualized by a fast determination method of grain orientation for Bragg-dip neutron transmission spectrum. In this paper, these imaging examples with the spectrum analysis methods and the reliabilities evaluated by optical/electron microscope and X-ray/neutron diffraction, are presented. In addition, the status at compact accelerator driven pulsed neutron sources is also presented.

Neutron spectrum change with thermal moderator temperature in a compact electron accelerator-driven neutron source and its effects on spectroscopic neutron transmission imaging

“…It was found that the difference of crystallite size between the simulated and theoretical Tr (E ) was 3.8%. This difference is almost acceptable because the difference of 3.8% is much smaller than the difference of 20 -30%, which was discussed in the crystallite size analysis [22]. The difference of texture in this case was 1.3%, and this is acceptable because of the same reason above.…”

“…In particular, the crystallite size was strongly affected, and the difference of the analyzed values reached to about 20%. In an example of the crystallite size analysis [22], the crystallites of welded and unwelded α-iron plates were evaluated, and then discussed the 20 -30% difference of crystallite size. The difference of 20% in analyzed values, which was caused by the 4.7 K change of T moderator , possibly cause incorrect evaluation of the crystallite size.…”

“…In the analyzed values of texture, the difference was 2.5%. The difference of texture was almost acceptable because larger than 20% difference was discussed in an example of texture analysis [22].…”

Neutron Diffraction and Diffraction Contrast Imaging for Mapping the TRIP Effect under Load Path Change

“…These Bragg edge features in the transmission spectra probed by wavelength resolved neutron imaging enable mapping and local analyses of crystalline phases and strains in 2D [33] and 3D [34,35]. As such, neutron diffraction contrast imaging can complement conventional neutron diffraction, and due to its superior spatial resolution it is ideal for investigating complex sample geometries, phase distributions and corresponding lattice strain fields [32,[34][35][36][37][38][39][40].…”

Crystalline Characterization of TlBr Semiconductor Detectors Using Wavelength-resolved Neutron Imaging

“…In particular, Bragg-dip imaging for single-crystal samples, such as Bragg-edge imaging for polycrystalline samples, can easily acquire two-dimensional crystal information. (7,8)…”