The Atomic and Magnetic Structure and Dynamics of Iron Phosphate Glasses

Author

Adrian C. Wright
Roger N. Sinclair
Joanna L. Shaw
Richard Haworth
Gaya Kanishka Marasinghe
D. E. Day, Missouri University of Science and TechnologyFollow
Paul A. Bingham
Susan D. Forder
Gabriel Julio Cuello
Henry E. Fischer
Jon W. Taylor

Abstract

Iron phosphate (Fe₂O₃-P₂O₅) glasses with a high Fe₂O₃ content are particularly interesting in that they exhibit short range antiferromagnetic (speromagnetic) ordering at low temperatures. Neutron scattering techniques have been employed to investigate the atomic and magnetic structure and dynamics of four iron phosphate glasses, as a function of their nominal composition between 30 and 44 mol% Fe₂O₃, and the data are compared with earlier structural models in which the Fe³⁺ cations are either tetrahedrally or 6-fold co-ordinated by oxygen. Fe²⁺ cations are also found to be present in 6-fold (trigonal-prismatic and/or octahedral) co-ordination. Neutron magnetic diffraction experiments yield information concerning the Fe-Fe distances and confirm the speromagnetic nature of the magnetic ordering, whilst a measurement of the magnetic inelastic scattering from vitreous 40Fe₂O₃.60P₂O₅ reveals the presence of dispersive magnetic excitations centred on the first magnetic diffraction peak at 0·82 å^-1. It is concluded that all four glasses have structures that are much more complicated than the above models would suggest and include Fe³⁺ cations in both tetrahedral and octahedral co-ordination. A comparison with the structure of the corresponding crystalline phases suggests that the glasses are nanoheterogeneous, with FePO₄-like regions (alternating FeØ₄^- and PØ₄⁺ corner sharing tetrahedra) and those having a more typical phosphate chain structure incorporating Fe²⁺/Fe³⁺ network modifying cations.

Recommended Citation

A. C. Wright and R. N. Sinclair and J. L. Shaw and R. Haworth and G. K. Marasinghe and D. E. Day and P. A. Bingham and S. D. Forder and G. J. Cuello and H. E. Fischer and J. W. Taylor, "The Atomic and Magnetic Structure and Dynamics of Iron Phosphate Glasses," Physics and Chemistry of Glasses: European Journal of Glass Science and Technology Part B, vol. 53, no. 6, pp. 227 - 244, Society of Glass Technology, Dec 2012.

Department(s)

Materials Science and Engineering

Keywords and Phrases

Antiferromagnetics; Atomic and magnetic structures; Corner-sharing tetrahedra; Crystalline phasis; Information concerning; Iron phosphate glass; Iron phosphates; Low temperatures; Magnetic diffraction; Magnetic excitations; Neutron magnetic diffraction; Neutron scattering techniques; Nominal composition; Phosphate chain; Structural models

International Standard Serial Number (ISSN)

0031-9090

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2012 Society of Glass Technology, All rights reserved.

Publication Date

01 Dec 2012