Correlation of the oxidation state of cerium in sol–gel glasses as a function of thermal treatment via optical spectroscopy and XANES studies

2004 ◽  
Vol 60 (8-9) ◽  
pp. 1873-1881 ◽  
Author(s):  
Zerihun Assefa ◽  
R.G. Haire ◽  
D.L. Caulder ◽  
D.K. Shuh
Keyword(s):  
Thermal Treatment ◽  
Optical Spectroscopy ◽  
Oxidation State ◽  
Sol Gel ◽  
Gel Glasses

Intense UV and visible up-conversion emissions from RE-doped SiO2–BaGdF5 nano-glass-ceramics

2018 ◽  
Vol 20 (32) ◽  
pp. 20910-20918 ◽  
Author(s):  
J. del-Castillo ◽  
A. C. Yanes
Keyword(s):  
Thermal Treatment ◽  
Sol Gel ◽  
Glass Ceramics ◽  
High Efficient ◽  
Gel Glasses

High-efficient UV and VIS up-conversion RE-doped nano-glass-ceramics comprising BaGdF5 nanocrystals, have been developed under thermal treatment of precursor sol–gel glasses.

Spectroscopic Investigations of Neptunium's and Plutonium's Oxidation States in Sol-Gel Glasses as a Function of Initial Valence and Thermal History

1996 ◽  
Vol 465 ◽  
Author(s):  
N. A. Stump ◽  
R. G. Haire ◽  
S. Dai
Keyword(s):  
Oxidation State ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Sol Gel ◽  
Solidification Process ◽  
Silica Matrix ◽  
Oxidation States ◽  
Temperature Spectra ◽  
Gel Glasses ◽  
Starting Solutions

ABSTRACTSeveral oxidation states of neptunium and plutonium, Pu(III), Pu(IV), Pu(VI), Np(IV), Np(V), and Np(VI), were studied in glasses prepared by a sol-gel technology. The oxidation state of these actinides in the sol-gel product was examined by absorption spectroscopy after solidification, aging, and thermal treatment. The oxidation state of the actinides in the starting solutions was essentially maintained through the solidification process of the silica matrix. However, during densification and removal of residual solvents at elevated temperatures, both actinides converted eventually to their tetra valent states while in the different sol-gel products. This finding is in accord with reports that tetravalent states of plutonium and neptunium are acquired in glass products prepared by dissolution of the actinide in molten glasses. Comparisons between room temperature spectra obtained from neptunium and plutonium in heated sol-gel products and from molten glass products showed subtle differences that can be related to the metal ion's environments.

scholarly journals Fundamental Chemistry and Materials Science of Americium in Selected Immobilization Glasses

1996 ◽  
Vol 465 ◽  
Author(s):  
R. G. Haire ◽  
N. A. Stump
Keyword(s):  
High Temperature ◽  
Oxidation State ◽  
Materials Science ◽  
Sol Gel ◽  
Melting Points ◽  
Pertinent Data ◽  
High Temperature Oxide ◽  
Temperature Oxide ◽  
Gel Glasses ◽  
Glass Matrices

ABSTRACTWe have pursued some of the fundamental chemistry and materials science of americium in three glass matrices, two being high-temperature (850° and 1400°C melting points) silicate-based glasses and the third a sol-gel glass. Optical spectroscopy was the principal investigating tool in the studies. One aspect of this work was to determine the oxidation state exhibited by americium in these matrices, as well as factors that control and/or may alter this state. We have noted a correlation between the oxidation state of the f-elements in the two high-temperature glasses with their high-temperature oxide chemistries. One exception was americium: although americium dioxide is the stable oxide encountered in air, when this dioxide was incorporated into the high-temperature glasses, only trivalent americium was found in the products. When trivalent americium was used to prepare the sol-gel glasses at ambient temperature, and after these products were heated in air to 800°C, again only trivalent americium was observed. Potential explanations for the unexpected behavior of americium is offered in the context of its basic chemistry. Experimental spectra, spectroscopie assignments and other pertinent data obtained in the studies are discussed.

TEM visualization of surface replicated acid and base catalyzed sol-gel glasses

1986 ◽  
Vol 44 ◽  
pp. 448-449
Author(s):  
George C. Ruben ◽  
Merrill W. Shafer
Keyword(s):  
Elevated Temperatures ◽  
Sol Gel ◽  
Basic Medium ◽  
Glass Transition Point ◽  
Structural Space ◽  
Acid And Base ◽  
Organometallic Precursors ◽  
New Processing ◽  
Gel Glasses ◽  
Physical Phenomena

Traditionally ceramics have been shaped from powders and densified at temperatures close to their liquid point. New processing methods using various types of sols, gels, and organometallic precursors at low temperature which enable densificatlon at elevated temperatures well below their liquidus, hold the promise of producing ceramics and glasses of controlled and reproducible properties that are highly reliable for electronic, structural, space or medical applications. Ultrastructure processing of silicon alkoxides in acid medium and mixtures of Ludox HS-40 (120Å spheres from DuPont) and Kasil (38% K2O &62% SiO2) in basic medium have been aimed at producing materials with a range of well defined pore sizes (∼20-400Å) to study physical phenomena and materials behavior in well characterized confined geometries. We have studied Pt/C surface replicas of some of these porous sol-gels prepared at temperatures below their glass transition point.

Photopatterning of hybrid sol–gel glasses: generation of volume phase gratings under visible light

2004 ◽  
Vol 398 (1-3) ◽  
pp. 151-156 ◽  
Author(s):  
M. Feuillade ◽  
C. Croutxé-Barghorn ◽  
L. Mager ◽  
C. Carré ◽  
A. Fort
Keyword(s):  
Visible Light ◽  
Sol Gel ◽  
Volume Phase ◽  
Gel Glasses

Bioencapsulation in Sol-Gel Glasses

1998 ◽  
Vol 519 ◽  
Author(s):  
L. Bergogne ◽  
S. Fennouh ◽  
J. Livage ◽  
C. Roux
Keyword(s):  
Sol Gel ◽  
Porous Silica ◽  
Silica Matrix ◽  
Whole Cells ◽  
The Past ◽  
Wide Range ◽  
Activity Of Enzymes ◽  
Gel Glasses ◽  
Micro Organisms

AbstractBioencapsulation in sol-gel materials has been widely studied during the past decade. Trapped species appear to retain their bioactivity in the porous silica matrix. Small analytes can diffuse through the pores allowing bioreactions to be performed in-situ, inside the sol-gel glass. A wide range of biomolecules and micro-organisms have been encapsulated. The catalytic activity of enzymes is used for the realization of biosensors or bioreactors. Antibody-antigen recognition has been shown to be feasible within sol-gel matrices. Trapped antibodies bind specifically the corresponding haptens and can be used for the detection of traces of chemicals. Even whole cells are now encapsulated without any alteration of their cellular organization. They can be used for the production of chemicals or as antigens for immunoassays.

Structural Stability of Azurin Encapsulated in Sol-Gel Glasses: A Fluorometric Study

2004 ◽  
Vol 30 (3) ◽  
pp. 205-214 ◽  
Author(s):  
Massimo Bottini ◽  
Almerinda Di Venere ◽  
Lutz Tautz ◽  
Alessandro Desideri ◽  
Paolo Lugli ◽  
...  
Keyword(s):  
Structural Stability ◽  
Sol Gel ◽  
Gel Glasses ◽  
Fluorometric Study
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