Synthesis of Molybdenum Disulphide

Because of the abundance of naturally-occurring molybdenite, there is little real incentive for the synthesis of molybdenum disulphide, but it has been synthesised in small quantities. In most earlier work syntheses have been carried out only for research purposes, either to investigate the synthesis reactions themseives or to compare the properties of natural and synthetic material. Larger quantities seem to have been synthesized only when a country with insufficient natural sources wanted to ensure a reliable indigenous supply. 

Several different processes have been used, the simplest being by the reaction of hydrogen sulphide with molybdenum pentachloride, or the reaction of sulphur vapour with molybdic oxide or molybdenum metal. The last of these processes has been called the SHS process (Self-Propagating High-Temperature Synthesis) and Russian workers have reported that the product is less contaminated with impurities and has almost identical lubricating properties to natural molybdenum disulphide. The crystal structure is considered in more detail later, but it seems probable that the initial product of syntheses has a disordered 

The differences between synthetic and naturally-occurring molybdenum disulphide are considered later. Unless otherwise specified, information in this book relates to the hexagonal crystal form obtained from natural molybdenite. 

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