In this contribution we analyzed the Vanadium speciation and structural local environment in two V-bearing Na-phosphate glasses by means of V K-edge X-ray Absorption Spectroscopy. The two glasses have starting molar proportions Na2O:V2O5:P2O5 equal to 45:10:45 (NaPV10) and 10:80:10 (NaPV80). Accurate analysis of the pre-edge peak of the two glasses allowed to determine the presence of[4]V5+ and[5]V5+ in NaPV80 and of[5]V4+ and[6]V4+ in NaPV10. EXAFS derived V–O distances for the two glasses are in agreement with literature data for the above mentioned V species. The determined V local geometries and the EXAFS derived bond distances have been used to build four structural models for[4]V5+,[5]V5+,[5]V4+ and[6]V4+ in the studied glasses; these models have been in turn used to calculate theoretical XANES spectra by means of the MXAN code. The partial contributions of each V species have been summed in order to fit the experimental XANES spectra of the two glasses. Iterative fitting of the structural parameters of each structural model resulted in a good agreement between experimental and theoretical XANES data. The analysis strategy used in the present work allowed to gain information of V speciation and on the structural local environment of the[4]V5+,[5]V5+,[5]V4+ and[6]V4+ species present in the analyzed glasses. Combined use of different spectral regions and data analysis routines allowed to successfully simulate XANES spectra and to gain an in depth knowledge of V local environment even in a complex system like amorphous glass containing different V species.

V K-Edge XANES Full Multiple Scattering Study of V-Bearing Phosphate Glasses

Benzi F.;Paris E.;Giuli G.
2021-01-01

Abstract

In this contribution we analyzed the Vanadium speciation and structural local environment in two V-bearing Na-phosphate glasses by means of V K-edge X-ray Absorption Spectroscopy. The two glasses have starting molar proportions Na2O:V2O5:P2O5 equal to 45:10:45 (NaPV10) and 10:80:10 (NaPV80). Accurate analysis of the pre-edge peak of the two glasses allowed to determine the presence of[4]V5+ and[5]V5+ in NaPV80 and of[5]V4+ and[6]V4+ in NaPV10. EXAFS derived V–O distances for the two glasses are in agreement with literature data for the above mentioned V species. The determined V local geometries and the EXAFS derived bond distances have been used to build four structural models for[4]V5+,[5]V5+,[5]V4+ and[6]V4+ in the studied glasses; these models have been in turn used to calculate theoretical XANES spectra by means of the MXAN code. The partial contributions of each V species have been summed in order to fit the experimental XANES spectra of the two glasses. Iterative fitting of the structural parameters of each structural model resulted in a good agreement between experimental and theoretical XANES data. The analysis strategy used in the present work allowed to gain information of V speciation and on the structural local environment of the[4]V5+,[5]V5+,[5]V4+ and[6]V4+ species present in the analyzed glasses. Combined use of different spectral regions and data analysis routines allowed to successfully simulate XANES spectra and to gain an in depth knowledge of V local environment even in a complex system like amorphous glass containing different V species.
2021
978-3-030-72004-9
978-3-030-72005-6
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11581/457635
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