Nano structural meaning to 3D XRD data: Converting the Bragg condition to crystallographic distortions and lattice strain fields topographically.
The objective of any materials characterization technique is to make the correlation between experimental measurements and Nano structural features/dimensions. The XRD technique is perfectly suited for this due to the fact that all measurements are made in the reciprocal space (ϴ or "The Bragg Space"). This inherently implies that small perturbations (femtometer scale) in the crystal lattice due to strain may be easily measured as they will appear at large angles (ϴ) and their "breadth" would be larger. In reciprocal space, small is large and large is small compared with "real" crystal space.
There are normally two important reciprocal space parameters that are conventionally recorded and monitored. Namely, the Bragg Peak Position and the FWHM. Both literature and experimental observations in real time indicate there may be many more subtle changes in the Bragg profile for individual topographic VOXELS on the sample surface than detectable using just the conventional "Bragg Peak Position and FWHM". Ideally, one would want to consider the "deviation from expected IDEAL Bragg profile" in order to fully quantify the crystallographic lattice distortions and strain fields. Bruker LEPTOS is an excellent tool to simulate the theoretical Bragg profile based on optics used.
We have converted the relative Bragg Peak Position to δd/d, the average lattice dilatation in the sampling VOXEL. Where d is d-spacing for the reflection (hkl) chosen.
We have also converted the relative FWHM to relative dislocation density, (ρ),using the approach of Hirsch et al.
Dislocation Density, ρ = (β2)/(9.b2)
b = Burgers Vector (Working on this one. Any suggestions? Would this be subject to the relative tilt from the reference Bragg angle of the voxel being examined?), and
β = Integrated Breadth (computed numerically from XRD profile data)
Please share your erudite thoughts and suggestions to improve. The objective is to benefit the entire XRD community and advance science.
https://www.flickr.com/photos/85210325@N04/28643920586/in/dateposted/
https://www.linkedin.com/pulse/nano-structural-meaning-xrd-data-converting-bragg-condition-ananth?trk=mp-reader-card
Dear colleague! I am not competent in this field and therefore can't help You as a professional. With respect. Viktor Ivanov
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