Experimental insight into the radiation resistance of zirconia-based americium ceramics.

Our works shows that the americium pyrochlore (241)Am(2)Zr(2)O(7) undergoes a phase transition to a defect-fluorite structure along with an unusual volume contraction when subjected to internal radiation from alpha-emitting actinides. Disorder relaxation proceeds through the simultaneous formation of cation antisites and oxygen Frenkel pairs. X-ray absorption spectroscopy at the Am-L(II) and the Zr-K edges reveals that Am-O polyhedra show an increasing disorder with increasing exposure.