Simulation of surface and grain boundary properties of alumina by molecular dynamics method

Simulation of surfaces and grain boundaries of α-alumina were carried out by the molecular dynamics method using an ionic pair potential. Simulation of five different surfaces, (1101), (1104), (1102), (1120), (0001), showed that, although a distorted structure formed at the surface, the calculated surface energies (γ_sv) were similar to each other. Simulations of five grain boundary misorientations (general, near Σ11, basal twin, Σ7, Σ3 grain boundaries) showed that both the structure and calculated grain boundary energy (γ_gb) were markedly different for each boundary. The values of γ_sv and γ_gb were similar to those reported in previous simulation studies, but were larger than the experimentally measured values. The energy ratios, γ_gb/γ_sv, were in the range 0.07 to 1.11, which was comparable to experimental values previously determined. The molecular dynamics simulation of surfaces and grain boundaries is shown to be a useful technique for the microstructural design of ceramics on the atomic scale.