SOLID STATE REDUCTION OF MoO 3 WITH CARBON VIA MECHANICAL ALLOYING TO SYNTHESIZE NANO-CRYSTALINE MoO 2

Abstract

In this research, effect of milling time on solid state reduction of MoO 3 with carbon has been investigated. It was found that mechanical activation of a mixture of MoO 3 and carbon at ambient temperature by high energy ball milling was not able to reduce MoO 3 to metallic molybdenum. MoO 3 was converted to MoO 2 at the first stage of reduction and peaks of the latter phase in X-ray diffraction patterns were detected when the milling time exceeded from 50 hours. The main effect of increased milling time at this stage was decreasing of MoO 3 peak intensities and significant peak broadening due to decrease in size of crystallites. After prolonged milling, MoO 3 was fully reduced to nano-crystalline MoO 2 and its mean crystallite size was calculated using Williamson–Hall technique and found to be 17.5 nm. Thermodynamic investigations also confirm the possibility of reduction of MoO 3 to MoO 2 during the milling operation at room temperature. But, further reduction to metallic molybdenum requires thermal activation at higher temperature near 1100 K. XRD and SEM techniques were employed to evaluate the powder particles characteristics.