Crystal structure refinement using Bloch-wave method for precession electron diffraction

Area of Science:

• Materials Science
• Crystallography
• Electron Microscopy

Background:

• Accurate crystal structure determination is crucial for understanding material properties.
• Electron diffraction offers unique insights into nanoscale crystalline structures.
• Accounting for complex scattering phenomena like multibeam interactions is essential for precise analysis.

Purpose of the Study:

• To develop and describe a novel procedure for crystal structure refinement.
• To integrate precession electron diffraction data with the Bloch-wave method for enhanced accuracy.
• To refine structural and dynamic diffraction parameters using a nonlinear least squares approach.

Main Methods:

• Utilized precession electron diffraction data.
• Employed the Bloch-wave method to account for multibeam dynamical scattering.
• Incorporated features of precession geometry into the refinement model.
• Minimized differences between measured and calculated intensities using nonlinear least squares.
• Tested the procedure on single silicon (Si) nanocrystals.

Main Results:

• Successfully refined the crystal structure of silicon nanocrystals.
• Demonstrated the procedure's ability to handle multibeam scattering effects.
• Analyzed the impact of reduced parameters on the quality of the refined structural model.

Conclusions:

• The described refinement procedure accurately determines crystal structures from precession electron diffraction data.
• The Bloch-wave method effectively accounts for dynamical scattering, improving model quality.
• The refinement procedure is integrated into the ASTRA software package.