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Abstract

In the actinide oxides of the fluorite structure, interstitial oxygen ions and oxygen vacancies are extremely mobile. The relevant data are discussed. In contrast, cation mobility is very limited. Consequently, a number of disturbing surface phenomena give rise to {apparent} cation tracer diffusion coefficients being a function of time and tracer position on the surface. Careful surface study and control allows these perturbing phenomena to be largely eliminated. Experiments on surface diffusion and bulk diffusion are reported. Cation diffusion rares vary very strongly with x, the deviation from stoichiometry. A pronounced minimum in cation diffusion at constant temperature is observed at slightly hypostoichiometric compositions. The totality of the data can only be explained if diffusion via cation vacancies, cation interstitials and formation of complexes of the type 2M**3+-V-o are invoked depending on oxygen-to- metal, O/M, ratio.

Additional information

Authors: MATZKE HJ JRC KARLSRUHE ESTAB. (GERMANY), JRC KARLSRUHE ESTAB. (GERMANY)
Bibliographic Reference: JOURNAL OF NUCLEAR MATERIALS, VOL. 114 (1983), PP. 121-135
Record Number: 1989122019800 / Last updated on: 1987-01-01
Category: PUBLICATION
Available languages: en