Key role of the cation interstitial structure in the radiation resistance of pyrochlores.

The annealing of the B cation interstitial is shown to drive the thermokinetic of the response to irradiations of A(2)B(2)O(7) pyrochlores. Molecular dynamics simulations evidenced that the annealing of interstitials created by irradiations depends upon the nature of B. As the coordination number of B decreases, the dumbbell interstitial is stabilized at the expense of the isolated interstitial. Unlike the isolated interstitials, the recombination of the dumbbells is thermally activated and hindered at low temperatures. The occurrence of dumbbells drives the structure towards the amorphous state.