CALCULATED STACKING-FAULT ENERGIES IN ALPHA-AL2O3

Atomistic lattice simulation was used to calculate the energies of sta cking faults in the aluminium sublattice of alpha-Al2O3. Three potenti als were employed. The first two were derived by first ascribing forma l charges to aluminium and oxygen (3.0 + and 2.0- respectively), and t hen by using two different methods to determine a short-range two-body interaction; the third was extracted from ab initio Hartree-Fock calc ulations. Stacking faults on the (0001) planes with a fault vector of 1/3[1010BAR] are high in energy (1.2-4.6 J m-2) and are sensitive to t he potential model used. The energies of stacking faults on the {1010B AR} and {1120BAR} planes with a fault vector of 1/3[1010BAR] are lower in energy (0.3-0.9 J m-2) and compare favourably with experiment.