TY  - JOUR
A1  - Wilke, Max
A1  - Partzsch, G. M.
A1  - Welter, E.
A1  - Farges, Francois
T1  - Redox Reaction In Silicate Melts Monitored By Static In-Situ Fe K-edge XANES Up To 1180 C
Y1  - 2007
ER  - 
TY  - JOUR
A1  - Wilke, Max
A1  - Partzsch, G. M.
A1  - Schmidt, C.
A1  - Farges, Francois
T1  - In-situ study of the iron species in silicate melts
Y1  - 2004
SN  - 0016-7037
ER  - 
TY  - JOUR
A1  - Wilke, Max
A1  - Partzsch, G. M.
A1  - Farges, Francois
T1  - XAFS of iron in silicate melt at high temperature
Y1  - 2004
SN  - 0024-4937
ER  - 
TY  - JOUR
A1  - Wilke, Max
A1  - Partzsch, G. M.
A1  - Bernhardt, Rita
A1  - Lattard, D.
T1  - Determination of the iron oxidation state in basaltic glasses using XANES at the K-edge
N2  - Fe K-edge X-ray absorption near edge structure (XANES) and Mossbauer spectra were collected on synthetic glasses of basaltic composition and of glasses on the sodium oxide-silica binary to establish a relation between the pre- edge of the XANES at the K-edge and the Fe oxidation state of depolymerised glasses. Charges of sample material were equilibrated at ambient pressure, superliquidus temperatures and oxygen fugacities that were varied over a range of about 15 orders of magnitude. Most experiments were carried out in gas-flow furnaces, either with pure oxygen, air, or different CO/CO2 mixtures. For the most reduced conditions, the samples charges were enclosed together with a pellet of the IQF oxygen buffer in an evacuated silica glass ampoule. Fe3+/SigmaFe x 100 of the samples determined by Mossbauer spectroscopy range between 0% and 100%. Position and intensity of the pre-edge centroid position vary strongly depending on the Fe oxidation state. The pre-edge centroid position and the Fe oxidation state determined by Mossbauer spectroscopy are nonlinearly related and have been fitted by a quadratic polynomial. Alternatively, the ratio of intensities measured at positions sensitive to Fe2+ and Fe3+, respectively, provides an even more sensitive method. Pre- edge intensities of the sample suite indicate average Fe co-ordination between 4 and 6 for all samples regardless of oxidation state. A potential application of the calibration given here opens the possibility of determining Fe oxidation state in glasses of similar compositions with high spatial resolution by use of a Micro-XANES setup (e.g., glass inclusions in natural minerals). (C) 2004 Elsevier B.V. All rights reserved
Y1  - 2004
SN  - 0009-2541
ER  - 
TY  - JOUR
A1  - Wilke, Max
A1  - Partzsch, G. M.
A1  - Bernhardt, Rita
A1  - Lattar, D.
T1  - Determination of the iron oxidation state in basaltic glasses using XANES at the K-edge
N2  - Fe K-edge X-ray absorption near edge structure (XANES) and Mossbauer spectra were collected on synthetic glasses of basaltic composition and of glasses on the sodium oxide-silica binary to establish a relation between the pre- edge of the XANES at the K-edge and the Fe oxidation state of depolymerised glasses. Charges of sample material were equilibrated at ambient pressure, superliquidus temperatures and oxygen fugacities that were varied over a range of about 15 orders of magnitude. Most experiments were carried out in gas-flow furnaces, either with pure oxygen, air, or different CO/CO2 mixtures. For the most reduced conditions, the samples charges were enclosed together with a pellet of the IQF oxygen buffer in an evacuated silica glass ampoule. Fe3+/Sigma Fe x 100 of the samples determined by Mossbauer spectroscopy range between 0% and 100%. Position and intensity of the pre-edge centroid position vary strongly depending on the Fe oxidation state. The pre-edge centroid position and the Fe oxidation state determined by Mossbauer spectroscopy are nonlinearly related and have been fitted by a quadratic polynomial. Alternatively, the ratio of intensities measured at positions sensitive to Fe2+ and Fe3+, respectively, provides an even more sensitive method. Pre- edge intensities of the sample suite indicate average Fe co-ordination between 4 and 6 for all samples regardless of oxidation state. A potential application of the calibration given here opens the possibility of determining Fe oxidation state in glasses of similar compositions with high spatial resolution by use of a Micro-XANES setup (e.g., glass inclusions in natural minerals). (c) 2004 Elsevier B.V. All rights reserved
Y1  - 2005
SN  - 0009-2541
ER  - 
TY  - JOUR
A1  - Wilke, Max
A1  - Farges, Francois
A1  - Partzsch, G. M.
A1  - Schmidt, C.
A1  - Behrens, Harald
T1  - Speciation of Fe in silicate glasses and melts by in-situ XANES spectroscopy
Y1  - 2007
ER  -