Atomic structure and solute segregation of a Σ=3, [110]/{111} grain boundary in an yttria-stabilized cubic zirconia bicrystal

The atomic structure and chemical composition of a Sigma = 3; [110]/{111} symmetric tilt grain boundary in an yttria-stabilized cubic zirconia bicrystal has been investigated by high-resolution transmission electron microscopy (HRTEM) and nanoprobe energy-dispersive X-ray spectroscopy. The experimental HRTEM images are compared with simulated images for a model obtained by lattice statics calculations. It is found that the grain boundary has two individual mirror symmetrical planes in cation and anion sublattices. In this case, the cations are forced to form sevenfold coordination in the vicinity of the boundary owing to the restraint of the boundary structure, while the cations in the cubic fluorite structure have eightfold coordination. The segregation of yttrium ions was experimentally detected at the Sigma = 3 boundary, a finding that is considered to be closely related to the change in the local coordination at the boundary.