Nature 293, 449 - 450 (08 October 1981); doi:10.1038/293449a0

Amorphous structure of metamict minerals observed by TEM

T. J. Headley^*, Rodney C. Ewing^† & Richard F. Haaker^†

^*Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
^†Department of Geology, University of New Mexico, Albuquerque, New Mexico 87131, USA

Metamict minerals are a special class of materials which were initially crystalline but have become amorphous because of accumulated structural damage caused by the radioactive decay of their constituent U and Th nuclides¹⁻³. Damage from particles and recoil nuclei may cause dramatic changes in physical, chemical, mechanical and structural properties of materials⁴⁻⁶. Thus, metamict minerals provide a natural example of the potential long-term effects of radiation damage in proposed crystalline radioactive waste forms⁷, such as the Sandia ceramic waste forms⁸⁻¹⁰, SYNROC¹¹⁻¹³, super-calcine¹⁴ or the tailored ceramics¹⁵. The determination of the microstructures of metamict materials, therefore, may help to predict long-term radiation effects in crystalline waste forms. This report presents the results of an examination by transmission electron microscopy (TEM) of a wide range of metamict silicate and complex Nb−Ta−Ti oxide minerals.

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