Title
Energetics and concentration of defects in Gd2Ti 2O7 and Gd2Zr2O7 pyrochlore at high pressure
Document Type
Article
Publication Date
2-1-2011
Abstract
Using first-principles calculations and complementary experiments, the defect formation energies and defect concentrations were calculated as a function of pressure. The results show that at high pressure, the defect formation energies decrease with pressure for both systems. In Gd 2Ti2O7, the dominant defect type is cation anti-site defect, the local structure around a defect is highly distorted, and the energetically favorable defect-defect interactions at shorter distance suggest the possibility of defect clustering. In Gd2Zr 2O7, anion Frenkel-pair defects are favored at all pressures and the dominant defect type involving a cation is a coupled defect of a cation anti-site and an anion Frenkel-pair defect. There are only minor distortions around the defects, and the defect-defect interactions are weak, which suggests almost-ideal non-interacting defect formation. Comparison of experimentally observed defect concentrations and those based on the calculated defect formation energies suggests that the defects formed at high pressure are better estimated with a concentrated limit approximation, while those formed at ambient pressure can be evaluated at a dilute limit approximation. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Publication Source (Journal or Book title)
Acta Materialia
First Page
1607
Last Page
1618
Recommended Citation
Wang, J., Zhang, F., Lian, J., Ewing, R., & Becker, U. (2011). Energetics and concentration of defects in Gd2Ti 2O7 and Gd2Zr2O7 pyrochlore at high pressure. Acta Materialia, 59 (4), 1607-1618. https://doi.org/10.1016/j.actamat.2010.11.025