Oxygen migration in A(2)B(2)O(7) pyrochlores

Atomic scale computer simulation has been used to predict activation energi es for oxygen migration. In total, 54 compounds with the A(2)B(2)O(7) pyroc hlore structure were simulated. In each case, oxygen migration was assumed to proceed via an oxygen vacancy mechanism with oxygen ions hopping between 48f sites. For some compounds the unoccupied 8a interstitial position play ed an important role in the migration mechanism. The results were analyzed using a contour map of activation energy versus A cation radius along the o rdinate and B cation radius along the abscissa. This identified areas of si milar cation radii, which exhibit lower activation energy. Results compare favourably with available experimental data. (C) 2001 Elsevier Science B.V, All rights reserved.