Atomistic simulations of structures and mechanical properties of polycrystalline diamond: Symmetrical 〈001〉 tilt grain boundaries

Abstract

Atomic structures and energies of symmetrical 〈001〉 tilt grain boundaries (GB's) in diamond have been calculated over a wide range of misorientation angle using a many-body analytic potential, and for some selected short-period grain boundaries with tight-binding and first-principles density-functional methods. The grain boundary energies from the tight-binding and first-principles methods are about 75% of those calculated with the analytic bond-order potential. The energy rankings of the GB's calculated with the empirical potential, however, are similar to that calculated from the tight-binding and the density functional approaches. Atomic-level energy and stress distributions calculated with the bond-order potential reveal relations between local interface reconstruction and the extent and value of hydrostatic and shear stresses. From the calculated local volume strain and hydrostatic stress fields, the atomic bulk moduli are evaluated, and zones of different elastic behavior in the vicinity of the interface are defined.