Self-radiation damage in Gd2Ti2O7

Weber, William J.; Wald, J.W.; Matzke, Hj.

doi:10.1016/0167-577x(85)90154-5

Cited by 110 publications

(78 citation statements)

References 12 publications

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“…However, when a full complement of impurities is present, the resulting zirconolite becomes metamict about as rapidly as pyrochlore. This effect appears to be different than what is observed in heavy-ion radiation-damage studies in which the transformation from one pure phase to the other is clearly observed before the material becomes metamict (Meldrum et al 2001;Wang et al 1999a;Wang et al 1999b;Weber et al 1985;). In these studies, pyrochlore transformed to a crystalline titanate with the fluorite crystal structure and then became metamict.…”

Section: X-ray Diffraction Resultscontrasting

confidence: 46%

The Status of Radiation Damage Experiments

Strachan¹,

Scheele²,

Icenhower³

et al. 2001

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SummaryThis is a status report on the progress of the radiation damage experiments that are being performed at the Pacific Northwest National Laboratory in support of the Plutonium Immobilization Program (PIP) to dispose plutonium that is surplus to the defense needs of the US. This report covers the progress of radiation damage from the decay of 238 Pu to the titanate phases that comprise the PIP ceramic. With the exception of brannerite, all the phases are represented in the specimens we are testing and characterizing. The phases appear to damage faster than anticipated from the information in the literature. Pyrochlore appears to become metamict 2 to 3 times faster. Zirconolite is more resistant, but this depends on what impurities are present.Radiation damage results in swelling of the specimens. After 650 days, the trend in the data suggest that swelling will continue as the damage process appears to be incomplete (it has not yet "saturated" or reached a steady-state condition). The decrease in density from swelling is between 8 % and 15%, based on measurements of the pyrochlore baseline and a zirconolite-rich ceramic. The linear expansion of the specimen dimensions is between 2% and 5%.The dissolution rate appears to be between 500 -1000 times greater for a 238 Pu-bearing pyrochlore baseline sample than for the corresponding 239 Pu specimen. Although we believe that this increase in rate is due to radiation damage, we cannot be absolutely certain because we did not manage to obtain SPFT data on these specimens before damage started to accumulate. It is possible that the increased rate is due to some effect related to the higher dose rate and radiation field near the 238 Pu specimens that we don't understand.

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Section: X-ray Diffraction Resultscontrasting

confidence: 46%

The Status of Radiation Damage Experiments

Strachan¹,

Scheele²,

Icenhower³

et al. 2001

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“…A full summary of work on pymchlore and zirconolite can be found in references [2,4,22]. The effect of a-decay on the pyrochlore phase Gd2Ti207 containing 244Cm and 240Pu has been extensively investigated by x-ray diffraction analysis and transmission electron microscopy [25,26]. At a dose of 3.1 x 10l8 a-decay events/g, the material became fully amorphous with no evidence of any residual crystallinity.…”

Section: Waste Forms For Piutoniummentioning

confidence: 99%

Crystalline Ceramics: Waste Forms for the Disposal of Weapons Plutonium

Ewing¹,

Lutze²,

Weber³

1996

Disposal of Weapon Plutonium

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“…Actinide-bearing waste forms will experience extensive α-recoil radiation damage, so it is important to understand the effect of radiation damage on the structure. Considerable work has been carried out characterizing the irradiation-induced, crystalline-to-amorphous transformation observed in titanate-based pyrochlores (Weber et al 1985(Weber et al , 1986Weber and Hess 1993). More recently, pyrochlores of Gd 2 (Ti 1-y Zr y ) 2 O 7 stoichiometry have been investigated that display a systematic decrease in susceptibility to radiation-induced amorphization with increasing Zr content (Wang et al 1999a(Wang et al , 1999b commensurate with a phase transition from an ordered pyrochlore structure to a defect fluorite structure.…”

Section: -16mentioning

confidence: 99%

Interfacial Chemistry and Engineering Annual Report 2000

Grate¹

2001

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+ exchange with K + in a layer lattice silicate mineral (e.g., muscovite). Muscovite is a 2:1 layer silicate containing structural layers of octahedrally coordinated Al(III) over-and underlain by layers of tetrahedrally coordinated Si(IV). Isomorphic substitutions in these layers lead to charge imbalance and a cation exchange capacity. These types of exchange reactions control the migration velocity of radio-cesium beneath leaked single shell tanks at Hanford and other DOE sites.Environmental Dynamics and Simulation researchers have 1) developed molecular models of this exchange reaction; 2) identified the key layer lattice silicates in Hanford sediments controlling Cs + exchange using advanced spectroscopic techniques such as synchrotron X-ray microscopy; 3) studied the thermodynamics and kinetics of Cs + adsorption and desorption on Hanford sediments; and 4) collaborated on the development of a multicomponent reactive transport model to forecast Cs migration velocities beneath leaked high level waste tanks at Hanford.

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Self-radiation damage in Gd2Ti2O7

Cited by 110 publications

References 12 publications

The Status of Radiation Damage Experiments

The Status of Radiation Damage Experiments

Crystalline Ceramics: Waste Forms for the Disposal of Weapons Plutonium

Interfacial Chemistry and Engineering Annual Report 2000

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