Atomic scale analysis of planar defects in polycrystalline diamond.
Planar defects in a polycrystalline diamond film were studied by high-resolution transmission electron microscopy (HRTEM) and high-resolution scanning transmission electron microscopy (STEM). In both modes, sub-Angstrom resolution was achieved by making use of two aberration-corrected systems; a TEM and a STEM C(s)-corrected microscope, each operated at 300 kV. For the first time, diamond in (110) zone-axis orientation was imaged in STEM mode at a resolution that allows for resolving the atomic dumbbells of carbon at a projected interatomic distance of 89 pm. Twin boundaries that show approximately the sigma3 CSL structure reveal at sub-Angstrom resolution imperfections; that is, local distortions, which break the symmetry of the ideal sigma3 type twin boundary, are likely present. In addition to these imperfect twin boundaries, voids on the atomic level were observed. It is proposed that both local distortions and small voids enhance the mechanical toughness of the film by locally increasing the critical stress intensity factor.
Erni
Rolf
R
FEI Electron Optics, PO Box 80066, 5600 KA Eindhoven, The Netherlands. rolf.erni@ua.ac.be
Freitag
Bert
B
Hartel
Peter
P
Müller
Heiko
H
Tiemeijer
Peter
P
van der Stam
Michiel
M
Stekelenburg
Mike
M
Hubert
Dominique
D
Specht
Petra
P
Garibay-Febles
Vincente
V