INFLUENCE OF OXYGEN ON ELECTRICAL-CONDUCTIVITY OF AMORPHOUS MOLYBDENUM SULFIDES

The electronic properties of hydrocracking catalysts such as molybdenum sulfides, obtained by sulfurization of oxides, are little known. Similar compounds can be obtained from amorphous molybdenum sulfides after contact with oxygen. The resulting by-products, corresponding to the general formula MoS(y)O(z), are still amorphous. The study of the polarization conductivity shows that in the sulfur-rich solids the action of oxygen creates a decrease of the potential energy, W(M), of the charge carriers and of the number of the sites, N, involved in the transport phenomenon. By contrast, for lower sulfur ratios, these parameters remain unchanged. The results show that the mechanism of conductivity can be ascribed to non-bonding orbitals due to sulfur and molybdenum atoms.