Correlation symmetry analysis of electron nanodiffraction from amorphous materials

Area of Science:

• Materials Science
• Condensed Matter Physics
• Electron Microscopy

Background:

• Angular symmetry in diffraction patterns is linked to the rotational symmetry of a material's atomic structure.
• Analyzing local symmetry in amorphous materials is challenging due to their disordered nature.

Purpose of the Study:

• To introduce and validate the angular symmetry coefficient as a novel method for quantifying local rotational symmetry in amorphous materials from electron nanodiffraction data.
• To address limitations of the angular power spectrum method, such as sensitivity to Fourier transformation artifacts and Friedel symmetry breakdown.

Main Methods:

• Calculating symmetry coefficients by averaging the angular autocorrelation function at characteristic symmetry angles.
• Comparing the symmetry coefficient method with the angular power spectrum approach using simulated and experimental electron nanodiffraction data.
• Utilizing electron nanodiffraction on a Pd-based metallic glass sample.

Main Results:

• Symmetry coefficients effectively extract local symmetry information without the artifacts associated with Fourier transformation and Friedel symmetry breakdown.
• The proposed method is more robust to experimental imperfections and sample thickness variations compared to the angular power spectrum.
• Experimental data from a metallic glass confirmed the potential for misleading information from the angular power spectrum and demonstrated the utility of symmetry coefficients.

Conclusions:

• The angular symmetry coefficient provides a reliable and more forgiving approach for determining angular symmetries in amorphous materials from electron nanodiffraction.
• This method enhances the analysis of local atomic arrangements in disordered materials.
• The findings contribute to advanced characterization techniques in materials science and condensed matter physics.