Tracing past migrations of uranium in Paleoproterozoic basins: New insights from radiation-induced defects in clay minerals

Geology ◽  
2010 ◽  
Vol 38 (11) ◽  
pp. 983-986 ◽  
Author(s):  
E. Morichon ◽  
D. Beaufort ◽  
T. Allard ◽  
D. Quirt
Keyword(s):  
Clay Minerals ◽  
Radiation Induced ◽  
Induced Defects

Radiation-induced defects in clay minerals: A review

2012 ◽  
Vol 277 ◽  
pp. 112-120 ◽  
Author(s):  
Th. Allard ◽  
E. Balan ◽  
G. Calas ◽  
C. Fourdrin ◽  
E. Morichon ◽  
...  
Keyword(s):  
Clay Minerals ◽  
Radiation Induced ◽  
Induced Defects

Radiation-induced Defects in Nonradioactive Natural Minerals: Mineralogical and Environmental Significance

2003 ◽  
Vol 792 ◽  
Author(s):  
Georges Calas ◽  
Thierry Allard ◽  
Etienne Balan ◽  
Guillaume Morin ◽  
Stéphanie Sorieul
Keyword(s):  
Clay Minerals ◽  
Defect Formation ◽  
High Specific Surface Area ◽  
Radiation Background ◽  
Geochemical Parameters ◽  
Wide Range ◽  
Natural Analogues ◽  
Radiation Induced ◽  
Electronic Defects ◽  
Induced Defects

ABSTRACTNatural short-lived radionuclides generate electronic defects in minerals, such as trapped electrons and positive holes, often associated with element impurities, which act as final traps over geological periods. Two main examples will be illustrated. The first example will concern the point defects, which are observed in clay minerals. The high specific surface area makes clay minerals sensitive to the geochemical radiation background and provides a record of the past occurrence of radionuclides in geological systems. In kaolinite, three types of hole-centers are trapped by oxygen atoms linked to Si- or Al-sites. An experimental dosimetry gives the paleodose, which can be used either to assess mean past U-concentration or for kaolinite dating, depending on the available geochemical parameters. The detection of past migrations of radioelements in natural analogues may be used in the safety assessment of radioactive waste disposals. The second example will concern the role of mineral impurities in defect formation and stabilization. Natural fluorites (CaF2) exhibit hole-and electron-centers trapped on several rare earths and oxygen impurities, often present at the ppm level, which are responsible for the wide range of coloration observed in natural fluorites. Ca colloids may form under severe irradiation and give rise to a characteristic absorption. The thermal stability of radiation-induced defects gives constraints on the evolution of fluorites as a function of temperature and time. Other minerals, such as apatite, confirm the importance of impurities in stabilizing radiation-induced defects over geological periods.

scholarly journals EPR Study of Paramagnetic Defects in Clay Minerals

Mineralogia ◽  
2007 ◽  
Vol 38 (2) ◽  
pp. 125-138
Author(s):  
Joanna Babińska ◽  
Krystyna Dyrek ◽  
Piotr Wyszomirski
Keyword(s):  
Clay Minerals ◽  
Metal Ion ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Resonance Spectroscopy ◽  
Radioactive Elements ◽  
Paramagnetic Resonance ◽  
Radiation Induced ◽  
Epr Signal ◽  
Induced Defects ◽  
Electron Paramagnetic

EPR Study of Paramagnetic Defects in Clay MineralsRadiation induced defects (RID-s) and transition metal ion impurities were revealed by EPR (Electron Paramagnetic Resonance) spectroscopy in kaolinites from a number of Polish deposits. Arelationship between the intensity of the EPR signals of the RID-s and quantity of radioactive elements was defined in these minerals. In one of the deposits of kaolinites (Wyszonowice) the EPR signal intensity depends on grain size. Other clay minerals studied (illites, montmorillonites) only show weak signals of the RID type.

Xenon ion irradiation of superconducting YBa2Cu3O7 thin films

1990 ◽  
Vol 48 (4) ◽  
pp. 92-93
Author(s):  
H. Watanabe ◽  
B. Kabius ◽  
B. Roas ◽  
K. Urban
Keyword(s):  
Defect Formation ◽  
Ion Irradiation ◽  
High Resolution Electron Microscopy ◽  
Structural Disorder ◽  
Flux Lines ◽  
Pinning Effect ◽  
Magnetic Flux Lines ◽  
Resolution Electron ◽  
Radiation Induced ◽  
Induced Defects

Recently it was reported that the critical current density(Jc) of YBa2Cu2O7, in the presence of magnetic field, is enhanced by ion irradiation. The enhancement is thought to be due to the pinning of the magnetic flux lines by radiation-induced defects or by structural disorder. The aim of the present study was to understand the fundamental mechanisms of the defect formation in association with the pinning effect in YBa2Cu3O7 by means of high-resolution electron microscopy(HRTEM).The YBa2Cu3O7 specimens were prepared by laser ablation in an insitu process. During deposition, a substrate temperature and oxygen atmosphere were kept at about 1073 K and 0.4 mbar, respectively. In this way high quality epitaxially films can be obtained with the caxis parallel to the <100 > SrTiO3 substrate normal. The specimens were irradiated at a temperature of 77 K with 173 MeV Xe ions up to a dose of 3.0 × 1016 m−2.

EXAFS STUDY ON RADIATION INDUCED DEFECTS

1986 ◽  
Vol 47 (C8) ◽  
pp. C8-1045-C8-1048
Author(s):  
T. BOLZE ◽  
J. PEISL
Keyword(s):  
Radiation Induced ◽  
Exafs Study ◽  
Induced Defects

Annealing of radiation-induced defects in ion-implanted AIIBVI single crystals

1989 ◽  
Vol 32 (3) ◽  
pp. 198-203
Author(s):  
A. N. Georgobiani ◽  
M. B. Kotlyarevskii ◽  
B. P. Dement'ev ◽  
V. N. Mikhalenko ◽  
N. V. Serdyuk ◽  
...  
Keyword(s):  
Single Crystals ◽  
Radiation Induced ◽  
Induced Defects ◽  
Ion Implanted

Formation of Drawing- or Radiation-Induced Defects in Germanium-Doped Silica Core Optical Fiber

1994 ◽  
Vol 33 (Part 2, No. 2B) ◽  
pp. L233-L234 ◽  
Author(s):  
Yoshinori Hayashi ◽  
Yuki Okuda ◽  
Hisamitsu Mitera ◽  
Keizo Kato
Keyword(s):  
Optical Fiber ◽  
Radiation Induced ◽  
Silica Core ◽  
Induced Defects

Raman scattering by radiation induced defects

1969 ◽  
Vol 30 (4) ◽  
pp. 253-254 ◽  
Author(s):  
I.R. Nair ◽  
C.E. Hathaway
Keyword(s):  
Raman Scattering ◽  
Radiation Induced ◽  
Induced Defects
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