Redox Effects on the Structure and Properties of Na-Mo-Fe-Phosphate Glasses

Abstract

Na-Mo-Fe-phosphate glasses were prepared with reducing and oxidizing raw materials and the effects of the different Fe2+/Fe3+ and Mo5+/Mo6+ ratios on glass structure and properties were determined. Mössbauer spectroscopy confirms significantly greater concentrations of Fe2+ ions in the reduced glasses and distorted Fe3+O4 sites preferred over the Fe3+O6 sites in the oxidized glasses. Raman spectroscopy reveals the presence of isolated Mo6+O6 sites in the oxidized glasses, and highly distorted Mo5+O5 sites in reduced Mo-rich glasses. The presence of specific Fe- and Mo-polyhedra is correlated with the average phosphate anion length, as characterized by high-pressure liquid chromatography. Generally, for the similar compositions, oxidized glasses have greater molar volumes than the reduced glasses, associated with the formation of isolated Mo6+O6 octahedra and the absence of highly crosslinked Mo5+OPO4 units. Tg increases with increasing Fe3+ fractions in the Fe-rich glasses, whereas for the Mo-rich glasses, Tg increases with greater Mo5+ fractions.

Department(s)

Materials Science and Engineering

Second Department

Nuclear Engineering and Radiation Science

Third Department

Chemistry

Keywords and Phrases

Iron phosphate glass; Molybdenum oxide; Mo¨ssbauer spectroscopy; Redox effect

International Standard Serial Number (ISSN)

0022-3093

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2021 Elsevier, All rights reserved.

Publication Date

01 Apr 2021

Link to Full Text

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