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Simulating Radiation-Induced Defect Formation in Pyrochlores

Published online by Cambridge University Press:  21 February 2013

David S.D. Gunn
Affiliation:
Scientific Computing Department, Science & Technology Facilities Council, Daresbury Laboratory, Sci-Tech Daresbury, Keckwick Lane, Daresbury, WA4 4AD, U.K.
John A. Purton
Affiliation:
Scientific Computing Department, Science & Technology Facilities Council, Daresbury Laboratory, Sci-Tech Daresbury, Keckwick Lane, Daresbury, WA4 4AD, U.K.
Ilian T. Todorov
Affiliation:
Scientific Computing Department, Science & Technology Facilities Council, Daresbury Laboratory, Sci-Tech Daresbury, Keckwick Lane, Daresbury, WA4 4AD, U.K.
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Abstract

The accuracy and robustness of new Buckingham potentials for the pyrochlores Gd2Ti2O7 and Gd2Zr2O7 is demonstrated by calculating and comparing values for a selection of point defects with those calculated using a selection of other published potentials and our own ab inito values. Frenkel pair defect formation energies are substantially lowered in the presence of a small amount of local cation disorder. The activation energy for oxygen vacancy migration between adjacent O48f sites is calculated for Ti and Zr pyrochlores with the energy found to be lower for the non-defective Ti than for the Zr pyrochlore by ∼0.1 eV. The effect of local cation disorder on the VO48f → VO48f migration energy is minimal for Gd2Ti2O7, while the migration energy is lowered typically by ∼43 % for Gd2Zr2O7. As the healing mechanisms of these pyrochlores are likely to rely upon the availability of oxygen vacancies, the healing of a defective Zr pyrochlore is predicted to be faster than for the equivalent Ti pyrochlore.

Type
Articles
Copyright
Copyright © Materials Research Society 2013 

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References

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