Synthesis and structural properties of Mo–Se–C sputtered coatings

Transition metal dichalcogenides have attracted considerable attention due to their self-lubricant properties. Their drawbacks, such us low load-bearing capacity or environmental sensitivity, have been partially overcome by alloying or doping with metals, carbon, or nitrides. Nevertheless, there is still a considerable potential for further improvement, since the majority of studies has been aimed at MoS2 and WS2 based coatings and the properties of diselenides remain almost unknown.Mo–Se–C coatings were prepared by non-reactive r.f. magnetron sputtering from carbon target with embedded MoSe2 pellets. The carbon content and Se/Mo ratio determined by electron probe microanalysis increased from 29 to 68 at.% and from 1.7 to 2.0, respectively, as a function of the decreasing number of pellets. The coating structure analyzed by X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy showed that Mo–Se–C was a mixture of amorphous carbon and Mo–Se phases, since no traces of molybdenum carbides were observed. Linear increase of the hardness from 0.7 (29 at.% C) to 4.1 GPa (68 at.% C) showed a significant improvement compared to values typical for pure MoSe2 coatin