Abstract
The susceptibility of uranophane, a uranyl sheet silicate, ideally Ca(UO2)2(SiO3OH)2(H2O)5. to ionizing irradiation has been evaluated by systematic irradiations with 200 keV elections over the temperature range 94 to 573 K. High-resolution transmission electron microscopy revealed that amorphous domains formed locally, concurrently with a gradual disordering of the entire structure. Amorphization doses at room temperature were 1.1 × 1O10 Gy for uranophane. 1.3 × 1O10 Gy for Sr- substituted uranophane. and 1.9 x 1O10 Gy for Eu-substituted uranophane: thus, there was an increase in amorphization dose with increasing average atomic mass. At 573 K. the amorphization dose of uranophane was 2.0 × 1O11 Gy. The temperature dependence of the amorphization dose of uranophane has two stages: ≤413 K and >413 K. Based on a defect accumulation model, the effective activation energies for amorphization at each stage are 0.0440 eV and 0.869 eV, respectively. This suggests that the presence of H2O (and OH-) reduce the energy deposition required to cause amorphization. Above 413 K. the amorphization dose increased due to the absence of H2O and OH- and the absence of radiolytic decomposition of H2O and OH-.
© 2015 by Walter de Gruyter Berlin/Boston
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Articles in the same Issue
- A molecular dynamics study of the behavior of sodium in low albite
- Observation and interpretation of paramagnetic defects in Brazilian and Central African carbonados
- Dissolution of gibbsite: Direct observations using fluid cell atomic force microscopy
- Polytypes and higher-order structures of antigorite: A TEM study
- An infrared spectroscopic study of the basic copper phosphate minerals: Cornetite, libethenite, and pseudomalachite
- Influence of F content on the composition of Al-rich synthetic phlogopite: Part I. New information on structure and phase-formation from 29Si, 1H, and 19F MAS NMR spectroscopies
- NMR evidence for formation of octahedral and tetrahedral Al and repolymerization of the Si network during dissolution of aluminosilicate glass and crystal
- Thermodynamic properties of hercynite (FeAl2O4) based on adiabatic calorimetry at low temperatures
- The formation of Sr silicates at low temperature and the solubility product of tobermorite-like Sr5Si6O16(OH)2 .5H2O
- Thermal equation of state of omphacite
- The effect of thermal decarbonation on stable isotope compositions of carbonates
- Synthetic MgAl2O4 (spinel) at high-pressure conditions (0.0001–30 GPa): A synchrotron X-ray powder diffraction study
- The stability of antigorite in the systems MgO-SiO2-H2O (MSH) and MgO-Al2O3-SiO2-H2O (MASH): The effects of Al3+ substitution on high-pressure stability
- The fusion curve of albite revisited and the compressibility of NaAlSi3O8 liquid with pressure
- Correction of secondary X-ray fluorescence near grain boundaries in electron microprobe analysis: Application to thermobarometry of spinel lherzolites
- An overgrowth model to explain multiple, dispersed high-Mn regions in the cores of garnet porphyroblasts
- Synchrotron X-ray diffraction study of the structure and dehydration behavior of todorokite
- Retrograde mineral reactions in saline fluid inclusions: The transformation ferropyrosmalite ↔ clinopyroxene
- The effect of ionizing radiation on uranophane
- Hydration, expansion, structure, and dynamics of layered double hydroxides
- Relict edenite in a garnet lherzolite from the Chinese Su-Lu UHP metamorphic terrane: Implications for metamorphic history
- Norrishite, K(Mn23+Li)Si4O10(O)2, an oxymica associated with sugilite from the Wessels Mine, South Africa: Crystal chemistry and 40Ar-39Ar dating
- The amblygonite (LiAlPO4F)-montebrasite (LiAlPO4OH) solid solution: A combined powder and single-crystal neutron diffraction and solid-state 6Li MAS, CP MAS, and REDOR NMR study
- An X-ray Rietveld, infrared, and Mössbauer spectral study of the NaMn(Fe1–xInx)2(PO4)3 alluaudite-type solid solution
- Gatelite-(Ce), a new REE-bearing mineral from Trimouns, French Pyrenees: Crystal structure and polysomatic relationships with epidote and törnebohmite-(Ce)
- Hydroxyl in clinopyroxene from the deep subducted crust: Evidence for H2O transport into the mantle
- A model for the structure of the hydrated aluminum phosphate, kingite determined by ab initio powder diffraction methods
- The crystal structure of synthetic autunite, Ca[(UO2)(PO4)]2(H2O)11