Sensitivity of quantitative symmetry measurement algorithms for convergent beam electron diffraction technique

Area of Science:

• Materials Science
• Crystallography
• Computational Materials Science

Background:

• Symmetry quantification is crucial for analyzing crystal structures.
• Existing methods may lack sensitivity to minor structural variations.
• Digital microscopy software offers platforms for developing advanced analytical tools.

Purpose of the Study:

• To evaluate the sensitivity of symmetry quantification algorithms (R_p and NCC) to structural changes.
• To develop and implement a symmetry quantification program using Digital Micrograph scripting.
• To assess the capability of these algorithms in detecting small strain values.

Main Methods:

• Simulated various convergent beam electron diffraction (CBED) patterns using the Bloch method.
• Developed a symmetry quantification program utilizing a Digital Micrograph (DM) script within Gatan digital microscopy software.
• Applied profile R-factor (R_p) and normalized cross-correlation (NCC) coefficient (γ) for symmetry analysis.

Main Results:

• The developed symmetry quantification program effectively analyzed CBED patterns.
• Both R_p and NCC coefficients demonstrated significant sensitivity to structural alterations.
• The algorithms successfully detected structural changes corresponding to strain values below 1%.

Conclusions:

• The R_p and NCC-based symmetry quantification algorithms are highly sensitive to minute structural modifications.
• These computational methods provide a reliable approach for detecting subtle strain in crystalline materials.
• The integration with digital microscopy software facilitates practical application in materials characterization.