Dr. Olga Shenderova
Department of Materials Science & Engineering,
North Carolina State University
4 PM, Thursday, Feb. 5, 1998
Room 101, Olin Physical Laboratory
The strength and fracture properties of chemical-vapor deposited diamond films are of critical importance for many applications. These properties have been attributed to the influence of grain boundaries, because CVD diamond films deposit as polycrystallites. We present two atomistic modeling techniques to characterize defect energies and fracture behavior of polycrystalline diamond. The first technique is a multiscale modeling method in which first-principles calculations on selected structures are combined with an analytic mesoscale model to obtain energies for symmetric <001> tilt grain boundaries over the entire misorientation range. The second technique is large-scale atomistic simulation of stress evolution and the dynamics of failure in notched polycrystalline diamond samples under an applied strain. The atomic structures of the triple line junctions and two-phase grain boundaries in diamond, containing graphite inclusions, will also be presented.