The atomistic mechanisms that determined the atomic coordination and local concentration of dopants at Σ5 (310)/[001] symmetrical tilt grain boundaries in Y2O3-doped ZrO2 were analyzed by using atomistic simulation techniques. The segregation mechanisms were found to be different to those in metals and metalloids, with local strain relief controlled by short-range interactions acting as the driving force for segregation; while long-range Coulombic interactions between the grain boundary region and the dopants resisted segregation. It was found that Y3+ ions segregated to a region within about 0.6nm of either side of the grain-boundary plane. The equilibrium local concentration of dopants in the vicinity of the grain boundary, governed by the balance between repulsive and attractive forces, was calculated to be 16.7mol% for 10.3mol%Y2O3-doped ZrO2. Co-segregation of an O2– vacancy was necessary to accommodate an Y3+ ion at a Σ5 grain boundary. The O2– vacancies played an important role in reducing the repulsion between the dopants and the grain boundary, and further relieving the local strain.

Numerical Analysis of Solute Segregation at Σ5 (310)/[001] Symmetrical Tilt Grain Boundaries in Y2O3-Doped ZrO2. T.Oyama, M.Yoshiya, H.Matsubara, K.Matsunaga: Physical Review B, 2005, 71[22], 224105 (11pp)