Ab initio prediction of charged species distribution at grain boundaries: Effects of structure and dopants

Funding Number

DE-AC05-00OR22725

Funding Sponsor

U.S. Department of Energy

Second Author's Department

Mechanical Engineering Department

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https://doi.org/10.1016/j.actamat.2024.120001

All Authors

Jing Yang, Mostafa Youssef, Bilge Yildiz

Document Type

Research Article

Publication Title

Acta Materialia

Publication Date

8-1-2024

doi

10.1016/j.actamat.2024.120001

Abstract

Understanding charged species transport in polycrystalline material is important in a wide range of applications. Due to defect segregation and space charge layer formation, the transport properties in the vicinity of the grain boundary are often drastically different from their bulk counterpart. In this work, we predict concentration profiles of charged species at Σ3 (100) twin boundary, Σ5 (210) [001] grain boundary, and Σ5 (310) [001] grain boundary of monoclinic ZrO2 by combining defect energetics from first-principles calculation and continuum level modeling. We show that at the close-packed Σ3 grain boundary, the space charge effect is negligible. The two Σ5 grain boundaries induce a positive space charge potential due to the segregation of oxygen vacancies. In the extended space charge layer, oxygen interstitials and electrons accumulate, leading to enhancement in oxygen diffusivity and n-type electronic conductivity. We survey doped ZrO2 and show that aliovalent dopants strongly change the magnitude of the space charge potential. In Cr- and Fe-doped ZrO2, we observe up to ten orders of magnitude increase in oxygen diffusion coefficient, and five orders of magnitude increase in electronic conductivity. These results show that defect redistribution at grain boundaries is one of the governing factors in determining transport properties in polycrystalline ZrO2, and that by such predictive modeling, a detailed understanding of point defect redistribution at extended defects is achievable.

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Article. Record derived from SCOPUS.

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