A Computational Study of Yttria-Stabilized Zirconia: II. Cation Diffusion
Name
Li_A computational II.pdf
Description
Accepted version
Size
1.7 MB
Format
Adobe PDF
Checksum (MD5)
e668d4ac5fbbd6edc73178276783b7c0
Author(s)
Dong, Yanhao
Qi, Liang
Li, Ju
Chen, I-Wei
Date Issued
March 2017
Journal
Acta Materialia
Publisher
Elsevier BV
Citation
Dong, Yanhao, Qi, Liang, Li, Ju and Chen, I-Wei. 2017. "A Computational Study of Yttria-Stabilized Zirconia: II. Cation Diffusion." Acta Materialia, 126.
Version
Author's final manuscript
Abstract
© 2017 Acta Materialia Inc. Cubic yttria-stabilized zirconia is widely used in industrial electrochemical devices. While its fast oxygen ion diffusion is well understood, why cation diffusion is much slower—its activation energy (∼5 eV) is 10 times that of anion diffusion—remains a mystery. Indeed, all previous computational studies predicted more than 5 eV is needed for forming a cation defect, and another 5 eV for moving one. In contrast, our ab initio calculations have correctly predicted the experimentally observed cation diffusivity. We found Schottky pairs are the dominant defects that provide cation vacancies, and their local environments and migrating path are dictated by packing preferences. As a cation exchanges position with a neighboring vacancy, it passes by an empty interstitial site and severely displaces two oxygen neighbors with shortened Zr-O distances. This causes a short-range repulsion against the migrating cation and a long-range disturbance of the surrounding, which explains why cation diffusion is relatively difficult. In comparison, cubic zirconia's migrating oxygen only minimally disturbs neighboring Zr, which explains why it is a fast oxygen conductor.
MIT Department
Massachusetts Institute of Technology. Department of Nuclear Science and Engineering
Massachusetts Institute of Technology. Department of Materials Science and Engineering
Terms of Use
Creative Commons Attribution-NonCommercial-NoDerivs License
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1016/j.actamat.2017.01.008
