Фазовая диаграмма системы Pb-S

К оглавлению: Другие диаграммы (Others phase diargams)

Pb-S (Lead-Sulfur) J.-C. Lin, R.C. Sharma, and Y.A. Chang The Pb-S system is characterized by an intermediate phase (PbS) with a narrow homogeneity range, which is formed at 50 at.% S and melts congruently at 1118 C. A eutectic close to pure Pb exists in the (Pb)-PbS region. A liquid miscibility gap, resulting in the formation of a monotectic reaction, exists in the PbS-(S) region with a eutectic close to pure S. The assessed phase diagram is based on thermodynamic modeling and calculations with review of the work of [05Fri], [61Bla], [66Mil], and [69Kul]. The calculated liquidus is in good agreement with the experimental data. The liquidus in the Pb-PbS region has an inflection point, which is indicative of a metastable liquid miscibility gap at lower temperatures. The Pb-S phase diagram has been calculated by assuming that the PbS phase is a line compound. Agreement between the calculated and the experimental phase diagram is good. The eutectic in the (Pb)-PbS region is very close to pure Pb. The eutectic in the PbS-(S) region is very close to pure S and has not been experimentally determined. S has negligible solid solubility in (Pb). The solubility of S in (Pb) at 300 C has been determined to be less than 0.0006 at.% S [39Gre]. The solubility of Pb in (S) is also negligible. The homogeneity range of PbS is very small. [74Leu] determined the deviation from stoichiometry to be ~1.7 x 10-5 mole of Pb per mole of PbS at 380 C. PbS is a semiconducting compound, which transforms from the cubic (NaCl-type) to the orthorhombic (GeS-type) structure at high pressures by a first-order transformation at ~25 kbar. 05Fri: K. Friedrich and A. Leroux, Metallurgie, 2, 536-539(1905) in German. 39Gre: J.N. Greenwood and H.W. Worner, J. Inst. Met., 115(2), 435-445 (1939). 61Bla: R.F. Blanks and G.M. Wills, Physical Chemistry of Process Metallurgy, Part 2, Interscience Publishers, New York, 991-1028 (1961). 66Mil: E. Miller and K.L. Komarek, Trans. TMS-AIME, 236, 832-840 (1966). 69Kul: G. Kullerud, Am. J. Sci., 267(A), 233-256 (1969). 74Leu: A.P. Leushina and M.V. Simonova, Z. Fiz. Khim., 48(5), 1187-1189 (1974) in Russian; TR: Russ. J. Phys. Chem., 48(5), 687-688 (1974). Published in Bull. Alloy Phase Diagrams, 7(4), Aug 1986. Complete evaluation contains 7 figures, 9 tables, and 41 references. 1