For the first time using a membrane zero-manometer, the vapor pressure S₂ over the surface of the PbS liquidus in the ternary system Cu–Pb–S were determined in the range 1100÷1400 K and 0÷760 mm Hg. Based on the thermodynamic calculation, the boundaries of the immiscibility of liquid alloys of the Cu–S, Pb–S, and Cu–Pb–S systems were determined and analytically described. Critical temperatures and pressures for immiscibility regions of sulfur-rich liquid alloys are characterized by high values: T^cr= 1520÷1880 K; P^cr=170÷510 atm. The crystallization surfaces of lead sulfide with electronic conductivity (p-type PbS) and with hole conductivity (n-type PbS) are calculated and analytically described, as well as the corresponding values of sulfur vapor pressure over the crystallization surface of lead sulfide. All analytical dependencies for 3D modeling were obtained and visualized using the OriginLab computer program

doi.org/10.32737/0005-2531-2021-4-35-42