Synthesis and characterization of novel barium iron phosphates: Insight into new structure types tailored by hydrogen atoms
- Fujian Provincial Key Laboratory of Advanced Materials, Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005, Fujian Province (China)
- Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, SK, Canada S7N 5E2 (Canada)
A significant gap in our knowledge of phosphate crystal chemistry is the lack of understanding of what controls the depolymerization of [PO{sub 4}] tetrahedra. A new route using phosphoric acid without any added water at 240 °C has been developed to synthesize two new compounds Ba{sub 2}Fe{sub 2}[H(PO{sub 3}OH){sub 2}][H(P{sub 2}O{sub 7}){sub 2}] and Ba{sub 2}Fe[H(P{sub 2}O{sub 7}){sub 2}], as well as a new polymorph β-BaFe{sub 2}(P{sub 2}O{sub 7}){sub 2} from annealing the former at ≥500 °C. Structural characterizations show that Ba{sub 2}Fe{sub 2}[H(PO{sub 3}OH){sub 2}][H(P{sub 2}O{sub 7}){sub 2}] features a novel 2D {sup 2}{sub ∞}([Fe{sub 2}[H(PO{sub 3}OH){sub 2}][H(P{sub 2}O{sub 7}){sub 2}]]{sup 4−}) layer structure containing both hydrogen-diphosphate [H(P{sub 2}O{sub 7}){sub 2}] and hydrogen-monophosphate [H(PO{sub 3}OH){sub 2}] groups, whereas Ba{sub 2}Fe[H(P{sub 2}O{sub 7}){sub 2}] and β-BaFe{sub 2}(P{sub 2}O{sub 7}){sub 2} possess an 1D chain structure and a 3D framework structure, respectively. These structures support a control of hydrogen on the depolymerization of [PO{sub 4}] groups and our work opens a new way for the synthesis of other novel phosphates using controlled water activities. - Graphical abstract: A new route of controlled water activities led to syntheses of three new compounds, indicating water plays a crucial role in the formation of novel phosphates. - Highlights: • A new mild thermal route for the synthesis of novel phosphates. • Water activities controlling the reaction: 2H{sub 3}PO{sub 4}↔H{sub 4}P{sub 2}O{sub 7}+H{sub 2}O. • Phosphate with mixed hydrogen-monophosphate and diphosphate groups. • H atoms in the structural backbone affect the depolymerization of PO{sub 4} groups.
- OSTI ID:
- 22334163
- Journal Information:
- Journal of Solid State Chemistry, Vol. 212; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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