Atomistic simulations of surface segregation of defects in solid oxide electrolytes

We performed atomistic simulations of yttria-stabilized zirconia (YSZ) and gadolinia-doped ceria (GDC) to study the segregation of point defects near (1 0 0) surfaces. A hybrid Monte Carlo–molecular dynamics algorithm was developed to sample the equilibrium distributions of dopant cations and oxygen...

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Bibliographic Details
Published in:Acta materialia 2010-04, Vol.58 (6), p.2197-2206
Main Authors: Lee, Hark B., Prinz, Friedrich B., Cai, Wei
Format: Article
Language:English
Subjects:
Applied sciences
Exact sciences and technology
Gadolinia-doped ceria
Metals. Metallurgy
Molecular dynamics
Monte Carlo
Segregation
Yttria-stabilized zirconia
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Summary:We performed atomistic simulations of yttria-stabilized zirconia (YSZ) and gadolinia-doped ceria (GDC) to study the segregation of point defects near (1 0 0) surfaces. A hybrid Monte Carlo–molecular dynamics algorithm was developed to sample the equilibrium distributions of dopant cations and oxygen vacancies. The simulations predict an increase of dopant concentration near the surface, which is consistent with experimental observations. Oxygen vacancies are also found to segregate in the first anion layer beneath the surface and to be depleted in the subsequent anion layers. While the ionic size mismatch between dopant and host cations has been considered as a driving force for dopant segregation to the surface, our simulations show that the correlation between individual point defects plays a dominant role in determining their equilibrium distributions. This correlation effect leads to more pronounced dopant segregation in GDC than in YSZ, even though the size mismatch between dopant and host cations is much greater in YSZ than in GDC.
ISSN:1359-6454
1873-2453
DOI:10.1016/j.actamat.2009.12.005