In situ X-ray analysis of MoO3 reduction by T. Leisegang, A. A. Levin, J. Walter, and D. C. Meyer

Crystal Research and Technology

Cryst. Res. Technol. 40, 95 (2005) - Abstract -

In situ X-ray analysis of MoO₃ reduction

T. Leisegang, A. A. Levin, J. Walter*, and D. C. Meyer

Dresden University of Technology, Institute of Structure Physics, 01062 Dresden, Germany
*CM Chemiemetall GmbH, Chemie Park Bitterfeld-Wolfen, Areal E, Niels-Bohr-Straße 5, 06749 Bitterfeld, Germany

Keywords	MoO₃, reduction, powder diffraction
PACS	61.10.Nz, 61.66.Fn, 82.33.Pt, 61.72.Cc
DOI	10.1002/crat.200410312

The reduction of MoO₃ to MoO₂ under hydrogen/argon atmosphere (5 vol. % H₂/95 vol. % Ar) in the temperature range 323 K…623 K was studied in situ by means of wide-angle X-ray scattering. It has been found that the starting material, MoO₃, consists of two different orthorhombic MoO₃ phases A and B with nearly the same structure parameters. The phase A (fraction of 37.1 wt%) describes the larger crystallites whereas the phase B (fraction of 62.9 wt.%) describes the smaller crystallites. Under the reduction to monoclinic MoO₂ phase during the heating, the thermal evolution of the phase fractions is different. A conclusion is drawn that MoO₂ is formed preferably in big crystallites. About 10 wt. % of MoO₂ has been found to form at 623 K resulting in about 69 wt. % after cooling to room temperature followed by holding in Ar/H₂ atmosphere about 24 h. Additionally, about 4.4 wt. % of the Mo₄O₁₁ oxide probably formed in large crystallites was detected in the reduced powder after the cooling.

The full text of this paper in pdf-Format:

If you have come directly to this page, click this symbol

to go to the CRT homepage.