Atomic scale volume and grain boundary diffusion elucidated by in situ STEM

Area of Science:

• Materials Science
• Condensed Matter Physics
• Physical Chemistry

Background:

• Diffusion is crucial in materials science for synthesis, processing, and applications.
• Fundamental knowledge gaps exist regarding atomic-scale observations of thermally stimulated volume diffusion.
• Mechanisms and kinetics of diffusion along defects like grain boundaries require further elucidation.

Purpose of the Study:

• To investigate volume diffusion processes of tungsten atoms in a metal matrix on the atomic scale.
• To provide direct, atomic-level observations of thermally stimulated diffusion.
• To differentiate between volume diffusion and diffusion along defects.

Main Methods:

• Utilized in situ high-resolution scanning transmission electron microscopy (HR-STEM).
• Observed the random movement of individual tungsten atoms within a crystalline lattice at elevated temperatures.
• Quantified diffusion kinetics through direct atomic tracking.

Main Results:

• Directly observed and confirmed random walk processes of single tungsten atoms.
• Quantified the kinetics of volume diffusion at the atomic scale.
• Successfully distinguished between diffusion within the crystal lattice (volume diffusion) and diffusion along defects.

Conclusions:

• Solidified and refined the understanding of the fundamental mechanism of volume diffusion.
• Provided unprecedented atomic-scale insights into diffusion in crystalline solids.
• Demonstrated the capability of HR-STEM for real-time atomic diffusion studies.