The Fe-O Coordination in Iron Phosphate Glasses by X-ray Diffraction with High-energy Photons

Abstract

Structures of (FeO)x(P2O5)1−x glasses with 0.2 ≤ x ≤ 0.5 are studied by x-ray diffraction using high energy photons from a synchrotron. Scattering intensities are obtained up to Qmax of 250 nm−1. P-O, Fe-O and O-O first-neighbour peaks are well resolved in the pair distribution functions. Constant P-O coordination numbers of 4.0 ± 0.1 with distances of 0.155 ± 0.001 nm are found as expected for PO4 tetrahedra. Mean Fe(II)-O coordination numbers of ~5 with distances of ~0.210 nm are extracted from fitting the Fe-O peaks where the oxygen coordination number of the minor fraction of 5-18% Fe(III) was set to six with Fe-O distances of 0.200 nm. The existence of FeO5 or strongly distorted FeO6 polyhedra instead of densely packed FeO6 octahedra for the Fe(II) sites is attributed to the mixed oxide effect. Fe3+ cations in rigid FeO6 octahedra hinder the Fe2+ cations in forming well defined octahedral environments.

Department(s)

Materials Science and Engineering

Sponsor(s)

Petroleum Research Fund

Keywords and Phrases

Glasses; Mechanical; Structural; Thermal; X-Ray Diffraction; Condensed matter

International Standard Serial Number (ISSN)

0953-8984

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2003 Institute of Physics - IOP Publishing, All rights reserved.

Publication Date

01 Sep 2003

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