A study of the natural α-recoil damage in zircon by infrared spectra

Wasilewski, P. J.; Senftle, F.E.; Vaz, J. E.; Thorpe, A. N.; Alexander, C. C.

doi:10.1080/00337577308232615

Cited by 35 publications

(13 citation statements)

References 11 publications

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“…We were surprised to note that the dose dependence of the absorption coefficient at 1666 cm −1 (i.e., ∼6 µm) reported by Wasilewski et al (1973) gave much higher values of the coefficient than ours for damaged samples, especially at high doses. For example, a value of 62.9 cm −1 for the coefficient was reported for a sample with a radiation dose of 8.3 × 10 18 α-events g −1 , and an error of 10% was estimated (Wasilewski et al 1973). Their absorption coefficient is almost double the value we obtained for a sample with a similar value of radiation dose.…”

Section: E ⊥ C E Ccontrasting

confidence: 84%

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Infrared spectra of Si-O overtones, hydrous species, and U ions in metamict zircon: radiation damage and recrystallization

Zhang

Salje

Ewing

2002

J. Phys.: Condens. Matter

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Radiation damage and recrystallization in natural zircons have been studied by analysing Si-O stretching overtones/combinations, hydrous species, and U-ion spectra in the frequency region between 1200 and 11 000 cm −1. The effects of radiation are characterized by a dramatic variation of intensity, a decrease in frequencies of multi-phonon bands (e.g., Si-O stretching overtones), a change of spectral profile of OH species, a formation of new OH species, and new signals related to U ions. The formation of new anisotropic OH species in the crystalline regions of metamict zircon is observed and this could account for the different thermal behaviour of OH species between metamict zircon and titanite during high-temperature annealing. The results imply systematic modifications of the local environments of the OH and U ions in the damage process. Both U 4+ and U 5+ spectra show dramatic variations during metamictization. We observe, for the first time, that as a result of radiation damage, the U 5+ signals near 6668 and 9030 cm −1 become undetectable at a dose of around 1.5 × 10 18 αevents g −1 while extra lines near 6650 and 8969 cm −1 appear. These variations are interpreted as radiation-induced local modifications in crystalline regions. The general shape of the U-ion spectrum of the crystalline zircon is somehow still preserved in highly damaged zircon. A decomposed zircon, consisting of ZrO 2 , SiO 2 , and ZrSiO 4 , shows spectral features different from those of metamict zircon samples. Thermal annealing of a highly damaged zircon leads to recovery of the structure of zircon, indicated by spectral changes of multiphonon bands and U ions, accompanied with the appearance of new OH species. The results confirm that the recrystallization process in heavily damaged zircon involves the decomposition of metamict ZrSiO 4 into SiO 2 and ZrO 2 near 1100 K and the significant crystal growth of ZrSiO 4 near 1400 K as indicated by the recovery of Si-O stretching overtones and U 4+ and U 5+ bands.

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Section: E ⊥ C E Ccontrasting

confidence: 84%

“…4%. We consider that the systematic difference between the data of Wasilewski et al (1973) and the three later measurements could be due to possible experimental errors. The values from Aines and Rossman (1986), Woodhead et al (1991a), and ours are more reliable and are fully reproducible.…”

Section: E Cmentioning

confidence: 99%

Infrared spectra of Si-O overtones, hydrous species, and U ions in metamict zircon: radiation damage and recrystallization

Zhang

Salje

Ewing

2002

J. Phys.: Condens. Matter

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“…PELLAS (1965) concluded that zircon ultimately decomposes to a mixture of its component oxides, SiO2 + Zr02. WASILEWSKI et al (1973) have supported these conclusions from infrared absorption spectral studies.…”

Section: Zirconolitesupporting

confidence: 77%

“…There is no evidence that the minerals become segregated into simple oxide phases even after receiving extremely large doses of radiation as proposed by PYATENKO (1970), WASILEWSKI et al (1973) andPELLAS (1965).…”

Section: Discussionmentioning

confidence: 98%

Alpha-recoil damage in natural zirconolite and perovskite.

Sinclair¹,

Ringwood²

1981

Geochem. J.

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Zirconolite (CaZrTi207) and perovskite (CaTi03) are key minerals in SYNROC , a ceramic material developed for the immobilization of high level nuclear reactor wastes. When these are incorporated in SYNROC, the long-lived radioactive actinide elements are preferentially partitioned into zirconolite and perovskite which are therefore subjected to the effects of alpha-recoil, resulting from the decay of these elements. These effects have been studied via X-ray and electron diffraction investigations of natural samples of zirconolite and perovskite of varying ages and varying uranium and thorium contents . The samples studied have received cumulative alpha doses ranging from 1.0 X 1018 to 1 .1 X 1020a/g. The upper limit corresponds to the alpha irradiation which would be received by the zirconolite in SYNROC containing 10 percent of high level waste over a period of 5 X 108 years.These studies show that zirconolites remain crystalline up to and beyond alpha doses of 2 X 1019a/g . This dose would have accumulated in such a SYNROC zirconolite after a million years of storage . Elec tron microscopy revealed that the grains were composed of small crystalline domains which possessed the defect fluorite-type structure. After a dose exceeding that which would be received by SYNROC in 100 million years, zirconolites appeared metamict when studied by X-ray diffraction . However, the elec tron micrographs and diffraction patterns clearly demonstrate that the mineral continues to retain a large degree of short range order and in no way resembles a glass. The density changes produced in these zir conolites by irradiation are small and range from 0 to 3 % at saturation.Perovskite samples which have SYNROC ages up to 20 ,000 years decrease in density by 1.8 ± 0.1 %. Their X-ray powder patterns are essentially unaffected. Comparative studies show that the perovskite lat tice is even more resistant to the effects of alpha-recoil than the zirconolite lattice. The results demonstrate that zirconolite and perovskite are extremely resistant to the effects of nuclear radiation and will provide stable crystal structures for the containment of the radioactive waste elements during the time required for the radioactivity to decay to safe levels (typically 101_106 years).

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“…1) nevertheless indicate that minerals incorporating the radio-nuclides U and Th in their lattices, suffer structural damage mainly due to the action of alpha recoils (cf. Wasiliewski et al 1973). The alpha particles themselves have rather subsidiary contribution (i.e., ca.…”

Section: Introduction: Radiation Damage In Mineralsmentioning

confidence: 99%

Review of effects of radiation damage on the luminescence emission of minerals, and the example of He-irradiated CePO4

Nasdala

Grambole²,

Ruschel

2013

Miner Petrol

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The accumulation of structural damage that is created in minerals upon corpuscular irradiation, has two apparently contrarious effects on their luminescence behaviour. First, irradiation may cause the generation of luminescent defect centres, which typically results in broad-band emissions. Such defect emissions are characteristic of low levels of radiation damage. Second, radiation damage depletes in general the luminescence of minerals, which is associated with broadenings and intensity losses of individual emission lines. Minerals that have suffered elevated levels of irradiation hence tend to be virtually non-luminescent. This review paper aims at giving an overview of the possible correlations of radiation damage and emission characteristics of minerals. After a brief, introductory summary of the damage-accumulation process and its causal corpuscular radiation, an array of examples is presented for how internal and/or external irradiation may change appreciably the emission of rock-forming and accessory minerals. As a detailed example for the complexity of changes of emissions upon damage accumulation, preliminary results of a case study of the photoluminescence (PL) of synthetic CePO 4 irradiated with 8.8 MeV He ions are presented. Irradiation-induced spectral changes include (i) the initial creation, and subsequent depletion, of a broad-band, defect-related PL emission of orange colour, and (ii) gradual broadenings and intensity losses of PL lines related to electronic transitions of rare-earth elements, eventually leading to gradual loss of their splitting into multiple Stark levels (shown for the 4 F 3/2 → 4 I 9/2 transition of Nd 3+).

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A study of the natural α-recoil damage in zircon by infrared spectra

Cited by 35 publications

References 11 publications

Infrared spectra of Si-O overtones, hydrous species, and U ions in metamict zircon: radiation damage and recrystallization

Infrared spectra of Si-O overtones, hydrous species, and U ions in metamict zircon: radiation damage and recrystallization

Alpha-recoil damage in natural zirconolite and perovskite.

Review of effects of radiation damage on the luminescence emission of minerals, and the example of He-irradiated CePO4

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