scholarly journals Paramagnetic defect centers in BESOI and SIMOX buried oxides

1993 ◽  
Vol 40 (6) ◽  
pp. 1755-1764 ◽  
Author(s):  
W.L. Warren ◽  
M.R. Shaneyfelt ◽  
J.R. Schwank ◽  
D.M. Fleetwood ◽  
P.S. Winokur ◽  
...  
Keyword(s):  
Paramagnetic Defect ◽  
Defect Centers

Investigation of radiation defects in steatite ceramics SK-1 and SNC by the EPR method

2021 ◽  
Vol 23 (1) ◽  
pp. 42-46
Author(s):  
K.Kh. Saidakhmedov ◽  
I. Nuritdinov ◽  
M.I. Baydjanov
Keyword(s):  
Glass Phase ◽  
Epr Spectra ◽  
Structural Defects ◽  
Radiation Defects ◽  
Γ Irradiation ◽  
Paramagnetic Defect ◽  
Amorphous Phases ◽  
Epr Method ◽  
Defect Centers ◽  
High Doses

The EPR spectra of γ- and n-γ-reactor irradiated steatite ceramics SK-1 and SNC has been studied. It is shown that structural defects of the E ′-center type are created in the structure of the SK-1 and SNC ceramics under the action of high doses of γ-irradiation. After n-γ-irradiation and additional annealing, paramagnetic defect centers such as interstitial Me2++e− ions are created in the structure of the SNC ceramics, which are caused by amorphization of the ceramic crystal phase and the creation of a Mg enriched glass phase at the interface between crystalline and amorphous phases.

Imaging of paramagnetic defect centers in solids

1986 ◽  
Vol 67 (2) ◽  
pp. 177-188 ◽  
Author(s):  
W Zommerfelds ◽  
M.J.R Hoch
Keyword(s):  
Paramagnetic Defect ◽  
Defect Centers

The Structure of SiO2-Sol-Gel Glasses Produced from Gels with Various Mole-Water per Mole-TEOS Ratios

1985 ◽  
Vol 61 ◽  
Author(s):  
George Kordas
Keyword(s):  
Gamma Ray ◽  
Sol Gel ◽  
Heat Treating ◽  
Paramagnetic Centers ◽  
Paramagnetic Defect ◽  
Defect Centers ◽  
Gamma Ray Irradiation ◽  
Gel Glasses

ABSTRACTSiO2-gels produced with 4,8, and 16 mol water per mol TEOS were densified up to 1000°C and then exposed to gamma-ray irradiation in order to produce paramagnetic defect centers. Various paramagnetic states were detected during densification of these gels, the formation of which depends on the mol water per mol TEOS ratio. In the gels O−2 ions were detected. The paramagnetic centers detected in the n = 16 gel with TH = 900°C were attributed to a non-bridging oxygen and an E'1-center. Three different O−2 ions, probably in interstitial positions, were detected in the n = 16-gel with TH = 1000°C. The CO−2 center was observed in the n = 8 gel with TH = 900°C. A variety of new components occur at TH = 1000°C in the n = 8 gel, the origin of which remains unresolved at present. The CH3, CO−2, and E1′-centers were detected in the n = 4 gel with TH = 700°C. The CO−2 and E′1 centers were preserved after heat treating the n = 4 gel at TH = 1000°C.

Color Centers in Glass Optical Fiber Waveguides

1985 ◽  
Vol 61 ◽  
Author(s):  
E. J. Friebele ◽  
D. L. Griscom
Keyword(s):  
Optical Fiber ◽  
Region Of Interest ◽  
Nuclear Radiation ◽  
Color Centers ◽  
Metal Fluoride ◽  
Paramagnetic Defect ◽  
Pure Silica ◽  
Defect Centers ◽  
Radiation Induced ◽  
Fiber Waveguides

ABSTRACTColor centers formed in the core and cladding of optical fiber waveguides by exposure to nuclear radiation can greatly increase the attenuation in the infrared spectral region of interest for optical communications. The radiation-induced paramagnetic defect centers in pure silica, silica doped with Ge, P, or B, and heavy metal fluoride glasses have been identified and thoroughly characterized by electron spin resonance (ESR) techniques. This paper will review the results of recent studies of color centers in optical fiber waveguide materials and their Identification via correlations of the radiation-induced optical absorptions and defect centers elucidated by ESR.

scholarly journals Influence of the synthesis conditions on the photoluminescence of silica gels

2003 ◽  
Vol 68 (12) ◽  
pp. 953-959 ◽  
Author(s):  
Ivana Hinic ◽  
Goran Stanisic ◽  
Zoran Popovic
Keyword(s):  
Photoluminescence Spectrum ◽  
Silica Gels ◽  
Silica Xerogel ◽  
Photoluminescence Spectra ◽  
Photoluminescence Band ◽  
Paramagnetic Defect ◽  
Synthesis Conditions ◽  
Nonstoichiometric Composition ◽  
Tert Butanol ◽  
Defect Centers

The photoluminescence spectra of silica xerogel samples synthesized with ethanol as solvent and xerogel where the ethanol was exchanged by water before drying are reported. In addition, the photoluminescence spectrum of a silica cryogel synthesized with tert-butanol as solvent was investigated. The samples were modified by formamide. Bands at 2.00, 2.20, 2.32 and 2.46 eV were identified. In the photoluminescence spectra of all samples. The band at 2.00 eV is caused by the presence of silane, and the band at 2.20 eV is connected with the nonstoichiometric composition of silica. The photoluminescence band at 2.32 eV was found to originate from the organic groups of the solvent. The origin of this band are E? defect centers, which is a prominenet paramagnetic defect in conventional a ? SiO2.

Record of Past Contact Between Altered Rocks and Radioactive Solutions Through Radiation-Induced Defects in Kaolinite

1990 ◽  
Vol 212 ◽  
Author(s):  
Philippe Ildefonse ◽  
Jean-Pierre Muller ◽  
Blandine Clozel ◽  
George Calas
Keyword(s):  
Ion Beam ◽  
X Rays ◽  
Paramagnetic Defect ◽  
Paramagnetic Resonance ◽  
Defect Centers ◽  
Different Types ◽  
Natural Analogues ◽  
Cumulative Radiation Dose ◽  
And Migration ◽  
Induced Defects

ABSTRACTA U-deposit located in hydrothermally altered tuff in Mexico, and two tropical weathering systems from Brazil and Cameroon were studied as natural analogues of radionuclide release and migration in the geosphere. In these alteration systems, kaolinite is the main secondary phyllosilicate associated with variable amounts of iron oxides. Defect centers are detected in natural kaolinites by means of electron paramagnetic resonance. The origin of the paramagnetic defect centers (PDC) is from radionuclide irradiation. This interpretation is supported by laboratory experiments on kaolinite using four different types of radiation: x-rays, γ-rays, and He+ and Pb2+ ion beam implantations. Several types of PDC (designated A-, A‵- and B-centers) are clearly identified and can be distinguished with respect to their relative stability. The A-center is stable over geological periods (on the order of 109 years) at surface temperatures. Moreover, it is shown that PDC’s in kaolinites reflect the cumulative radiation dose.PDC’s in kaolinite have been used to trace radionuclide migration in the three natural alteration systems studied. The kaolinites investigated show a significant concentration of PDC’s which corresponds to background natural irradiation. The different types of PDC detected may record successive irradiations of kaolinite directly linked to geochemical conditions prevailing during and after kaolinite growth. Because of their different thermal stability, these different PDC–s may be considered to have formed at different time periods. This makes a unique tool for tracing the dynamics of the transfer of radionuclides and allows the use of kaolinite as an in-situ dosimeter. Because some of the geological settings chosen for nuclear wastes are located in kaolinite-bearing strata, PDC dosimetry could be used in a safety assessment of these wastes.

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