Flame generation of two new precursors of vanadyl pyrophosphate
Journal Article
·
· Journal of Solid State Chemistry
- Johns Hopkins Univ., Baltimore, MD (United States)
- Universite de Technologie de Compiegne (France)
Two new vanadyl pyrophosphate precursors were produced in a single step operation using a counterflow diffusion flame burner. The technique consists of adding a vanadium and a phosphorus halide to the fuel stream of hydrogen-oxygen flames. Particles nucleate and grow in the flame to an average diameter between 5 and 30 nm. Upon exiting the flame, powders are collected on two stainless steel strips and their crystalline structures are analyzed by X-ray diffraction and Fourier-transform infrared spectroscopy. A strong effect of flame temperature on the crystalline structure of the powders produced is observed. When a high temperature flame is used, the powder collected is a mixture of VOPO{sub 4} {center_dot}2H{sub 2}O and (VOPO{sub 4}){sub 1-x}(VOHOP{sub 4}){sub x}{center_dot}2.6H{sub 2}O. This mixture forms {gamma}-VOPO{sub 4} upon subsequent reheating at 750{degrees}C in a oxidizing atmosphere, and transforms into (VO){sub 2}P{sub 2}O{sub 7} in an oxygen-free atmosphere at 700{degrees}C. When a lower temperature flame is used, the powder collected is (VOPO{sub 4}){sub 1-x}(VOHPO{sub 4}){sub x}{center_dot}2.9H{sub 2}O, which transforms at 750{degrees}C into {Beta}-VOPO{sub 4} in an oxidizing atmosphere and to (VO){sub 2}P{sub 2}O{sub 7} at 700{degrees}C in an oxygen-free atmosphere. Structural differences between the two vanadyl pyrophosphates are observed. These differences are discussed in terms of the ability of (VO){sub 2}P{sub 2}O{sub 7} to accommodate various disordered and polytypic structures.
- OSTI ID:
- 390901
- Journal Information:
- Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 1 Vol. 124; ISSN 0022-4596; ISSN JSSCBI
- Country of Publication:
- United States
- Language:
- English
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