Morphology and phase modifications of MoO{sub 3} obtained by metallo-organic decomposition processes

• Published in: Materials research bulletin Vol. 45; no. 11
• Main Authors: Barros Santos, Elias de, Martins de Souza e Silva, Juliana, Odone Mazali, Italo
• Format: Journal Article
• Language: English
• Published: United States 15-11-2010
• Subjects: DECOMPOSITION; MATERIALS SCIENCE; MOLYBDENUM OXIDES; MONOCLINIC LATTICES; ORTHORHOMBIC LATTICES; OXYGEN; RAMAN SPECTROSCOPY; SCANNING ELECTRON MICROSCOPY; SYNTHESIS; X-RAY DIFFRACTION
• ISSN: 0025-5408; 1873-4227
• DOI: 10.1016/J.MATERRESBULL.2010.06.057

Molybdenum oxide samples were prepared using different temperatures and atmospheric conditions by metallo-organic decomposition processes and were characterized by XRD, SEM and DRS UV/Vis and Raman spectroscopies. Variation in the synthesis conditions resulted in solids with different morphologies and oxygen vacancy concentrations. Intense characteristic Raman bands of crystalline orthorhombic {alpha}-MoO{sub 3}, occurring at 992 cm{sup -1} and 820 cm{sup -1}, are observed and their shifts can be related to the differences in the structure of the solids obtained. The sample obtained under nitrogen flow at 1073 K is a phase mixture of orthorhombic {alpha}-MoO{sub 3} and monoclinic {beta}-MoO{sub 3}. The characterization results suggest that the molybdenum oxide samples are non-stoichiometric and are described as MoO{sub x} with x < 2.94. Variations in the reaction conditions make it possible to tune the number of oxygen defects and the band gap of the final material.