Yttrium segregation and oxygen diffusion along high-symmetry grain boundaries in YSZ
RL Gonzalez-Romero and JJ Melendez, JOURNAL OF ALLOYS AND COMPOUNDS, 622, 708-713 (2015).
A study by Molecular Dynamics of yttrium segregation to high-symmetry grain boundaries of yttria-stabilized zirconia has been performed for different amounts of dopants. After an initial (and short) transient, segregation reaches a steady regime in which the concentration of the defect species at the grain-boundaries does not change in time. The maximum concentration of yttrium is reached at the grain-boundary planes, while oxygen vacancies screen the electric field created by segregation. Segregation of yttrium does not change appreciably the coefficients for oxygen diffusion along the grain boundaries, but instead modifies those for bulk diffusion. This effect is rationalized in terms of the rearrangement of the oxygen vacancies at the vicinities of the yttrium cations. The activation energies vary smoothly with the concentration of yttria for all the boundaries. Our data for diffusion coefficients and activation energies compare fairly well with experimental values when segregation is explicitly taken into account. (C) 2014 Elsevier B.V. All rights reserved.
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