Heavy-ion irradiation effects in the ABO{sub 4} orthosilicates: Decomposition, amorphization, and recrystallization
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6057 (United States)
- Department of Nuclear Engineering and Radiological Sciences and Department of Geological Sciences, The University of Michigan, Ann Arbor, Michigan 48109-2104 (United States)
The effects of displacive, heavy-ion irradiation on the properties of synthetic single-crystals of ZrSiO{sub 4} (zircon), HfSiO{sub 4} (hafnon), tetragonal ThSiO{sub 4} (thorite), and monoclinic ThSiO{sub 4} (huttonite) have been investigated. All four ABO{sub 4}-type orthosilicate materials became amorphous in a process that exhibited a two-stage dependence on temperature when irradiated by 800 keV Kr{sup +} or Xe{sup +} ions in the temperature range of 20 to 1100 K. The critical amorphization temperature above which amorphization did not occur increased in the following order: huttonite, zircon, hafnon, thorite. At temperatures below 500 K, the tetragonal and monoclinic polymorphs of ThSiO{sub 4} required approximately the same ion fluence for amorphization. Monoclinic ThSiO{sub 4} is, therefore, not {open_quotes}more resistant{close_quotes} to radiation damage than the tetragonal-symmetry form, but instead, its amorphous phase recrystallizes at a lower temperature. A model that accounts for the observed two-stage behavior was developed and used to calculate the recrystallization activation energies for both stages. When irradiated with heavy ions above a certain characteristic temperature, an unexpected decomposition was observed in which all four ABO{sub 4} orthosilicates phase separated into the crystalline oxides: ZrO{sub 2}, HfO{sub 2}, or ThO{sub 2} plus amorphous SiO{sub 2}. {copyright} {ital 1999} {ital The American Physical Society}
- OSTI ID:
- 304257
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 59, Issue 6; Other Information: PBD: Feb 1999
- Country of Publication:
- United States
- Language:
- English
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