Role of cation choice in the radiation tolerance of pyrochlores

Journal Article · Fri Dec 21 00:00:00 EST 2012 · RSC Advances

DOI:https://doi.org/10.1039/C2RA22745B· OSTI ID:1063699

Devanathan, Ramaswami ^[1]; Gao, Fei ^[1]; Sundgren, Christina J. ^[1]

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1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

We have used atomistic computer simulations to study anion diffusion coefficients and the response to swift heavy ion irradiation of Gd₂TixZr_2-xO₇ pyrochlore for x values of 0, 0.5, 1, 1.5 and 2. In Gd₂Ti₂O₇, thermal energy deposition per unit length of 12 keV/nm results in a cylindrical amorphous track of radius 2 nm in good agreement with experiment. The volume swelling of the track is 4%, which suggests that it is partially amorphous. Gd vacancies and Ti interstitials along with cation exchange play a role in damage accumulation in the titanate. In sharp contrast, Gd₂Zr₂O₇ does not swell and merely transforms from fluorite to pyrochlore under the same conditions. The activation energy barrier for oxygen hopping by the vacancy mechanism in these pyrochlores is 0.26-0.44 eV. The radiation tolerance of gadolinium zirconate pyrochlore is related to the efficient annihilation of cation Frenkel pairs, the low energy cost and negligible volume expansion associated with the resulting cation exchange, and efficient annealing of anion sublattice damage.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1063699
• Report Number(s): PNNL-SA-91744; 47464; KC0201020
• Journal Information: RSC Advances, Vol. 3, Issue 9; ISSN 2046-2069
• Publisher: Royal Society of Chemistry
• Country of Publication: United States
• Language: English

Related Subjects

pyrochlore
thermal spike
molecular dynamics
Environmental Molecular Sciences Laboratory