The atomic and magnetic structure and dynamics of iron phosphate glasses

Abstract

Iron phosphate glasses, xFe2O3.(100−x)P2O5 {hereinafter denoted xFe.(100−x)P}, are not only of potential commercial importance for the immobilisation of plutonium containing and other high level nuclear wastes but are also of great scientific interest in that, at low temperatures, they exhibit short range antiferromagnetic (speromagnetic) ordering, as demonstrated by an earlier neutron magnetic diffraction investigation and by magnetic susceptibility measurements. However, studies of this system are complicated by the fact that the glasses may contain a variable amount of Fe, depending on the preparation conditions. The crystallography of the FeO–Fe2O3–P2O5 system is also extremely complex, as may be seen from Table 1 of Ref. 5. In a previous paper, a subset of the authors presented neutron diffraction data for three samples, with nominal compositions 30Fe.70P, 40Fe.60P and 44Fe.56P, and compared the resulting real space total correlation functions, T(r), with two structural models, one, originally proposed for vitreous 44Fe.56P, comprising alternating FeO4 and PO4 tetrahedra (cf. quartz polymorphs of FePO4) plus O=PO3 units, where O represents a bridging oxygen atom, and the other, for vitreous 40Fe.60P, based on (Fe3O12) clusters, as found in crystalline Fe3(P2O7)2. It was concluded that the structure is much more compliThe atomic and magnetic structure and dynamics of iron phosphate glasses