Atomic-level Structure Studies of Rare-earth Doped Sodium Phosphate Glasses Using High Energy X-ray Diffraction and Complementary Techniques PDF Download
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Author: Faisal Amir
Publisher:
ISBN: 9780355432800
Category : Electronic dissertations
Languages : en
Pages : 340
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Book Description
Author: Faisal Amir
Publisher:
ISBN: 9780355432800
Category : Electronic dissertations
Languages : en
Pages : 340
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Book Description
Author: Erandi Svetlana Gunapala
Publisher:
ISBN:
Category : Glass
Languages : en
Pages : 208
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Book Description
Author: Mehdi Ali
Publisher:
ISBN:
Category : Glass
Languages : en
Pages : 134
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Book Description
Author: Sooraj Hussain Nandyala
Publisher: Trans Tech Publications Ltd
ISBN: 303813242X
Category : Technology & Engineering
Languages : en
Pages : 300
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Book Description
The aim of this work is to review the latest developments in glass science and technology. It presents various types of glass, of both academic and technological importance, in which the host is doped with rare-earth ions.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 12
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Book Description
Because of their unusually good chemical durability, iron phosphate glasses are a natural candidate for a nuclear waste disposal glass. We have studied the effects of UO2 high-level waste on the structure of iron phosphate glasses with both neutron and high-energy x-ray diffraction using the GLAD instrument of the Intense Pulsed Neutron Source and the 1-BM bending magnet beamline of the Advanced Photon Source, respectively. The results of neutron scattering, which is mostly sensitive to correlations involving light atoms i.e. O-O, Fe-O and P-O, suggest the main structural features of the base glass are largely unaffected by the addition of UO2. The nearest-neighbor P-O, Fe-O and O-O peaks remain at the same position in real space and their intensities scale approximately with concentration. These findings are consistent with the earlier results of Raman scattering and EXAFS on the Fe-K edge wherein both cases the spectra remain similar to the base glass. High-energy x-ray scattering which is sensitive to correlations involving the heavier atoms and thus complements the neutron measurements, is also consistent with uranium occupying interstitial sites in the relatively undisturbed base glass structure. However, important questions remain as to the precise local structure and oxidation state of uranium in these glasses.
Author: Kailing Zhang
Publisher:
ISBN: 9781267938244
Category : Electronic dissertations
Languages : en
Pages : 86
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Author: Pramod Kothari
Publisher: LAP Lambert Academic Publishing
ISBN: 9783659630217
Category :
Languages : en
Pages : 92
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Book Description
Glass is the most important substrate material suitable for fabrication of passive and active integrated optical components. The refractive index of a glass substrate is very close to that of the optical fibers (n=1.48), which minimizes the coupling losses between glass waveguides and optical fibers. Glass has excellent transparency in the visible and near infrared spectral regions and can easily be made in different sizes and shapes with very high homogeneity. As an amorphous material distinct from crystals, it is easier to produce polarization insensitive integrated optical components in glass. In addition, Glass has a high threshold to optical damage; it is mechanically very rigid and relatively inexpensive. Glass is also suitable host for rare earth ions. This has allowed for the fabrication of optical amplifiers and lasers.
Author: Herbert G. Lipson
Publisher:
ISBN:
Category : Absorption spectra
Languages : en
Pages : 80
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Book Description
Absorption spectra were used to determine the effect of modifier ions on the splitting and relative intensity of neodymium spectral terms in germanate and other glasses. The behavior of spectral components is related to the degree of inhomogeneous broadening and changes in the site symmetry of the neodymium ion. A similarity between the wavelength position of neodymium term levels and their total width in glasses and crystalline neodymium oxide has been observed. Fluorescence spectra for neodymium, erbium, and holmium ions in sodium germanate glass are reported and the absorption lines involved in excitation with both lamp and laser sources discussed. The lines of an argon-ion laser are found to be more convenient and powerful sources for the excitation of rare earth ion fluorescence than mercury vapor or tungsten lamp sources. The energy level diagram of neodymium in sodium germanate glass was determined from absorption and fluorescence peak spectra. A relationship between the strength of infrared absorption bands involved in cross-relaxation processes and the extent of neodymium fluorescence quenching was observed. Fluorescence conversion efficiencies comparable or higher than those of commercial laser glasses are found for neodymium in sodium germanate glass by both laser and lamp excitation methods. Germanate glasses show good potential as laser hosts for a number of rare earth ions. (Author).
Author: Manuel Ross
Publisher: Springer
ISBN: 3319286463
Category : Science
Languages : en
Pages : 124
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Book Description
This thesis provides the first successful study of jump diffusion processes in glasses on the atomic scale, utilizing a novel coherent technique. This new method, called atomic-scale X-ray Photon Correlation Spectroscopy or aXPCS, has only recently been proven to be able to capture diffusion processes with atomic resolution in crystal systems. With this new toolkit for studying atomic diffusion in amorphous systems, new insight into basic processes in a wide range of technically relevant materials, like fast ionic conductors, can be obtained.
Author: Mevlüt Karabulut
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
"The atomic structure, glass forming and crystallization characteristics, and the chemical durability of vitreous binary iron phosphates of approximate batch composition 40Fe2O3-60P2O5 (mol%) and those containing up to 40 wt% of one or more common nuclear waste components such as Na2O, CS2O, SrO, UO2, or Bi2O3 have been investigated. The analytical tools used are Fe-57 Mössbauer, x-ray absorption, x-ray photoelectron, and Raman spectroscopies, high energy x-ray and neutron diffraction techniques, differential thermal analysis (DTA), and the product consistancy test (ASTM C-1285-94). The excellent chemical durability of iron phosphate glasses containing nuclear waste components is indicated by dissolution rates (at 90 °C in distilled water) as low as 10−10 to 10−11 g/cm2/min. When melted in air at 1100 to 1200°C, these iron phosphate melts reach a redox equilibria corresponding to a Fe(II)/Fe(III) ratio less than 0.51. The Fe(II) content increases with increasing melting temperature and when melted in reducing atmospheres. However, the glass forming ability of the melts decreases when the Fe(II)/Fe(III) ratio exceeds ca. 0.67. Both species of iron ions are coordinated with 5 to 5.5 near neighbor oxygen ions. The phosphorous-oxygen network is dominated by (P2O-- )4− dimer units. The iron-oxygen coordination and the phosphorous-oxygen network do not appreciably depend on the type or the concentration of the waste elements. The waste ions, which are situated outside the second shell coordination environment of iron and phosphorus ions, are not a major influence on the chemistry of the iron-oxygen-phosphorus host matrix. Therefore the addition of waste components does not cause major changes in properties such as the chemical durability of the iron phosphate host matrix. Vitreous iron phosphate host matrices appear to be a low cost and effective alternative to borosilicate glasses for vitrifying selected nuclear wastes"--Abstract, leaf iv
