XRD analysis of nanolayered molybdenum disulfide obtained by sol-gel technology

Abstract

The deposition of molybdenum disulfide by sol-gel technology was investigated. Initial mixture for the synthesis was prepared from ultrafine powders of metals and elemental sulfur. Synthesis was performed slowly during 2 h by precipitation of the molybdenum hydroxide from aqueous 0.001M solution of MoSO2 and sodium hydroxide with constant stirring. By morphology obtained layers of particles of molybdenum disulfides deposited on silicon substrate have bimodal distribution: from 0.1 to 0.2 μm with a maximum at 0.15-0.18 μm; and from 0.4 to 5.0 μm with a maximum at 3.0 μm. It was established that obtained molybdenum oxide hydroxide particles do not coagulate within 48 h, which is associated with the formation of micellar positively charged particles. According to the data of X-ray diffraction and Raman spectroscopy disulfide particles have a layered structure, and the main phase is a hexagonal disulfide with a space group of symmetry P63 / mmc. By X-ray images it was established that increasing the sulfur content in the mixture in the synthesis of nanostructured molybdenum disulfide is reflected on reducing the intensity and number of reflections phase, as well as on reducing the rate and the maximum temperature of combustion. Upon sulfur excess higher than 15% by weight, the phase of mainly hexagonal molybdenum disulfide was observed in the product. By estimation of zeta potential, the value of zeta potential was 54 mV, clearly indicating that the particles obtained in aqueous suspension are not coagulating due to the predominance of the processes of repulsion of the particles.