Crystal chemical constraints on the formation of actinide pyrochlores

The pyrochlore structure type, A/sub 1-2/B2O6Y/sub 0-1/ Fd3m Z=8, is a common constituent of polyphase, crystalline waste forms. Naturally occurring minerals with the same structure often occur in the radiation damaged, electron-diffraction amorphous, ''metamict'' state; and therefore, a principal concern with phases of this structure type is the effect of alpha-recoil damage associated with the presence of actinides. In this paper we outline crystal chemical constraints on the formation of novel actinide pyrochlores. 24 refs., 1 fig., 2 tabs