In situ chemical reaction of Nb{sub 12}O{sub 29} in a high resolution gas reaction cell microscope

Journal Article · Sat Jun 01 04:00:00 EDT 1996 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1006/jssc.1996.0214· OSTI ID:390903

Sayagues, M J; Hutchison, J L ^[1]

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1. Univ. of Oxford (United Kingdom)

Solid-state oxidation-reduction of a nonstoichiometric Nb{sub 12}O{sub 29} (NbO{sub 2,417}) with monoclinic cell was studied using a JEOL 4000 EX HRTEM equipped with a gas reaction cell in which the oxide was oxidized and then reduced by sequentially introducing O{sub 2} and H{sub 2}. The oxidation yielded other block structures with higher oxygen content. The first step of the oxidation mechanism, involving formation of lamellar defects of composition Nb{sub 11}O{sub 27} (NbO{sub 2,450}), could be elucidated with great certainty. Nb{sub 10}O{sub 25} (a metastable polymorph of NbO{sub 2,500}) was formed as a final stage of the oxidation process. Subsequent reduction led to a nearly ordered Nb{sub 12}O{sub 29} phase suggesting that such an oxidation-reduction reaction is a reversible process. When Nb{sub 12}O{sub 29} was directly reduced, NbO was found to grow on the surface of the crystal.

• Sponsoring Organization: USDOE
• OSTI ID: 390903
• 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

Related Subjects

40 CHEMISTRY
MONOCLINIC LATTICES
NIOBIUM OXIDES
OXIDATION
REDUCTION
STOICHIOMETRY
TRANSMISSION ELECTRON MICROSCOPY