Electron microscopy study of some molybdenum oxide crystals

We have studied by electron microscopy and selected area diffraction the morphology and structure of the different oxides which are obtained by air-burning of a filament of molybdenum. The electron microscopy observation shows several morphologies depending on the filament temperature and the pressure of the oxidation vessel. Experimental pressures of 100, 300, 600 and 700 Torr were used and, for each, the temperature ranged from 650 to 1250°C. Platelets, needles, mosaic and spheroids have been the most frequent microcrystal shapes. Orthorhombic MoO3 and Mo4O11 structures have been identified. The oxide formation evolves from needles and mosaic (at lowest pressure and temperature) to spheroids (at the highest ones). © 1980.