In order to study the phase equilibria of the transition metal sulfides, it becomes important to establish the PS2 (partial pressure of sulfur)-composition isotherms. The process for controlling the PS2 (it is rather difficult to control it experimentally) and how to corelate it to make the isotherm of the sulfides is also described here. The profile of the isotherm in some transition metal sulfides is introduced from published literature. Moreover, the kind of information obtained from these isotherms is also explained.
