THERMAL REDUCTION OF MOO3

X-my photoelectron spectroscopy (XPS) and laser Raman spectroscopy (LRS) have been used to examine the thermal reduction products of thin-film molybdenum trioxide under flowing hydrogen or nitrogen gases. Some of the LRS measurements were made in situ during the reduction reaction using a custom quartz cell reactor. Thermal reduction of MoO3 was studied over the range 350-730-degrees-C. At most temperatures, MoO2 and MoO3 were the only species measured by LRS. Two intermediate molybdenum species, believed to be Mo(IV) and Mo(V), were detected by XPS, along with MoO2 and MoO3. In one set of samples reduced in the 450-degrees-C range, localized reduction could be attributed to the presence of impurities. From these impurities, a chemical "front" is propagated, and at the front a metastable species intermediate between MoO3 and MoO2 is identified.