Use of electron backscatter diffraction patterns to determine the crystal lattice. Part 1. Where is the Bragg angle?

Area of Science:

• Materials Science
• Crystallography
• Diffraction Physics

Background:

• Deriving crystal structure and phase parameters from Kikuchi diffraction patterns relies on precise Bragg angle extraction.
• Automated analysis of Kikuchi patterns is crucial for reproducible crystallographic data.

Purpose of the Study:

• To investigate the accuracy and reproducibility of automated Bragg angle extraction from simulated Kikuchi patterns.
• To identify and quantify systematic errors in lattice parameter determination from Kikuchi diffraction.

Main Methods:

• Utilized the first derivative of the lattice profile to automatically determine band widths in simulated Kikuchi patterns.
• Analyzed the impact of various factors, including projection center, wavelength, and lattice plane traces, on lattice parameter accuracy.

Main Results:

• A linear offset in the mean lattice parameter distribution was observed, correlating with the mean atomic number (Z) of the material phase.
• Analyzing multiple Kikuchi bands reduces errors compared to single-band analysis.
• Higher image resolution, longer wavelengths, or higher interference orders offer diminishing returns in accuracy.

Conclusions:

• Automated lattice parameter determination from Kikuchi patterns is subject to a systematic error dependent on the material's atomic number.
• Careful consideration of band selection and pattern acquisition parameters is necessary for reliable crystallographic analysis.