Structural features of iron‐phosphate glass

Abstract

This paper reports a study and discusses the role of Fe ions in the inhibition of corrosion of iron phosphate glasses. The structure of the 40Fe2O3–60P2O5 (mol%) glass, having a confirmed dissolution rate in aqueous solution at 90°C superior to borosilicate glasses, was investigated. Samples were crystallized at characteristic temperatures defined by differential thermal analysis and analyzed by X‐ray diffraction. Crystalline phases of Fe2Fe[P2O7]2 and Fe4[P2O7]3 were detected. The hyperfine parameters from the Mössbauer spectrum indicate that both Fe2+ and Fe3+ ions are in octahedral coordination, and 18% of the Fe3+ ions in the starting batch are reduced to Fe2+ ions after melting. The broad and symmetric spectra centered in g≈2.0 from the EPR measurements indicate the presence of two or more Fe interacting ions occupying sites of relatively high local symmetry.

Vitrification of U3O8 in iron aluminium phosphate matrices including Bi2O3 as uranium surrogate

“…The leaching test results are shown in the following Fig. 3, depicting a reasonable chemical stability and corrosion resistance to the water attack due to the high percentage of PAOAFeAO bonds, as was reported also for the only binary glasses by Reis et al [8]. This bonding jointly with the pres-ence of U (4+ to 6+) giving rise to a strong bonding between PO 4 chains and the Fe 3+ tetra or octahedral coordinated with the oxygen and the uranium included in the composition of these special glasses.…”

Enhancing glass anode performance for lithium‐ion batteries via crystallization

“…It is clear to see that T g decreases with the increasing Fe 2 O 3 content, that is, from 887 K for 20FeP glass to 771 K for 50FeP glass, as indicated by the dotted arrow in Figure 1B. Generally, the phosphate glass is constructed by corner‐sharing PO 4 tetrahedra forming chains or rings 43 . With the increase of Fe 2 O 3 content, the bridging oxygens (BOs) by P‐O‐P gradually transforms to the non‐bridging oxygens (NBOs) linked via Fe‐O‐P since both Fe 2+ and Fe 3+ ions are in octahedral coordination rather than acting as glass formers 22,43–45 .…”

“…Generally, the phosphate glass is constructed by corner-sharing PO 4 tetrahedra forming chains or rings. 43 With the increase of Fe 2 O 3 content, the bridging oxygens (BOs) by P-O-P gradually transforms to the non-bridging oxygens (NBOs) linked via Fe-O-P since both Fe 2+ and Fe 3+ ions are in octahedral coordination rather than acting as glass formers. 22,[43][44][45] This leads to the depolymerization of the cross-linking network structure of the glass, and thus the reduction in T g .…”

“…43 With the increase of Fe 2 O 3 content, the bridging oxygens (BOs) by P-O-P gradually transforms to the non-bridging oxygens (NBOs) linked via Fe-O-P since both Fe 2+ and Fe 3+ ions are in octahedral coordination rather than acting as glass formers. 22,[43][44][45] This leads to the depolymerization of the cross-linking network structure of the glass, and thus the reduction in T g . For 20FeP and 30FeP glass samples, the O/P ratio is less than 3.5, indicating a metaphosphate network structure.…”