Atomic scale analysis of planar defects in polycrystalline diamond

Area of Science:

• Materials Science
• Nanotechnology
• Solid-State Physics

Background:

• Polycrystalline diamond films possess unique mechanical and electronic properties.
• Understanding planar defects is crucial for optimizing film performance.
• Previous studies lacked atomic-scale resolution for defect characterization.

Purpose of the Study:

• To investigate planar defects in polycrystalline diamond films at sub-Angstrom resolution.
• To characterize the atomic structure of twin boundaries and other defects.
• To correlate defect structures with mechanical properties.

Main Methods:

• Utilized aberration-corrected high-resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy (STEM).
• Employed a 300 kV Cs-corrected TEM and a 300 kV Cs-corrected STEM.
• Achieved sub-Angstrom resolution imaging, enabling visualization of atomic dumbbells in diamond.

Main Results:

• Achieved unprecedented sub-Angstrom resolution in STEM imaging of diamond in (110) zone-axis orientation.
• Resolved atomic dumbbells of carbon at a projected interatomic distance of 89 pm.
• Identified imperfections in sigma3 CSL twin boundaries, including local distortions and atomic-level voids.
• Observed deviations from the ideal sigma3 twin boundary symmetry.

Conclusions:

• Imperfections at twin boundaries, such as local distortions and voids, are present in polycrystalline diamond films.
• These atomic-scale defects are proposed to enhance the mechanical toughness of the diamond film.
• The findings provide insights into structure-property relationships for advanced diamond materials.