Accurate predictions of iron redox state in silicate glasses: A multivariate approach using X-ray absorption spectroscopy

2016 ◽  
Vol 101 (3) ◽  
pp. 744-747 ◽  
Author(s):  
M. Darby Dyar ◽  
Molly McCanta ◽  
Elly Breves ◽  
C.J. Carey ◽  
Antonio Lanzirotti
Keyword(s):  
Absorption Spectroscopy ◽  
Redox State ◽  
Silicate Glasses ◽  
Multivariate Approach ◽  
X Ray ◽  
Iron Redox ◽  
X Ray Absorption ◽  
Iron Redox State

scholarly journals Structure of NaFeSiO4, NaFeSi2O6, and NaFeSi3O8 glasses and glass-ceramics

2020 ◽  
Vol 105 (9) ◽  
pp. 1375-1384 ◽  
Author(s):  
Mostafa Ahmadzadeh ◽  
Alex Scrimshire ◽  
Lucy Mottram ◽  
Martin C. Stennett ◽  
Neil C. Hyatt ◽  
...  
Keyword(s):  
Glass Phase ◽  
Redox State ◽  
Glass Ceramics ◽  
Isothermal Heat Treatment ◽  
X Ray ◽  
Heat Treated ◽  
High Level ◽  
Iron Redox ◽  
X Ray Absorption ◽  
Iron Redox State

Abstract The crystallization of iron-containing sodium silicate phases holds particular importance, both in the management of high-level nuclear wastes and in geosciences. Here, we study three as-quenched glasses and their heat-treated chemical analogs, NaFeSiO4, NaFeSi2O6, and NaFeSi3O8 (with nominal stoichiometries from feldspathoid, pyroxene, and feldspar mineral groups, i.e., Si/Fe = 1, 2, and 3, respectively) using various techniques. Phase analyses revealed that as-quenched NaFeSiO4 could not accommodate all Fe in the glass phase (some Fe crystallizes as Fe3O4), whereas as-quenched NaFeSi2O6 and NaFeSi3O8 form amorphous glasses. NaFeSi2O6 glass is the only composition that crystallizes into its respective isochemical crystalline polymorph, i.e., aegirine, upon isothermal heat-treatment. As revealed by Mössbauer spectroscopy, iron is predominantly present as fourfold-coordinated Fe3+ in all glasses, though it is present as sixfold-coordinated Fe3+ in the aegirine crystals (NaFeSi2O6), as expected from crystallography. Thus, Na-Fe silicate can form a crystalline phase in which it is octahedrally coordinated, even though it is mostly tetrahedrally coordinated in the parent glasses. Thermal behavior, magnetic properties, iron redox state (including Fe K-edge X-ray absorption), and vibrational properties (Raman spectra) of the above compositions are discussed.

Variations in the redox state of As and Fe measured by X-ray absorption spectroscopy in aquifers of Bangladesh and their effect on As adsorption

2010 ◽  
Vol 25 (1) ◽  
pp. 34-47 ◽  
Author(s):  
Takaaki Itai ◽  
Yoshio Takahashi ◽  
Ashraf Ali Seddique ◽  
Teruyuki Maruoka ◽  
Muneki Mitamura
Keyword(s):  
Absorption Spectroscopy ◽  
Redox State ◽  
X Ray ◽  
As Adsorption ◽  
X Ray Absorption

scholarly journals Sulfur K-edge x-ray absorption spectroscopy: A spectroscopic tool to examine the redox state of S-containing metabolites in vivo

1998 ◽  
Vol 95 (11) ◽  
pp. 6122-6127 ◽  
Author(s):  
A. Rompel ◽  
R. M. Cinco ◽  
M. J. Latimer ◽  
A. E. McDermott ◽  
R. D. Guiles ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Redox State ◽  
X Ray ◽  
Spectroscopic Tool ◽  
X Ray Absorption

Tin valence and local environments in silicate glasses as determined from X-ray absorption spectroscopy

2008 ◽  
Vol 354 (27) ◽  
pp. 3142-3151 ◽  
Author(s):  
David A. McKeown ◽  
Andrew C. Buechele ◽  
Hao Gan ◽  
Ian L. Pegg
Keyword(s):  
Absorption Spectroscopy ◽  
Silicate Glasses ◽  
X Ray ◽  
Local Environments ◽  
X Ray Absorption
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