Фазовая диаграмма системы Pb-Te

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Pb-Te (Lead-Tellurium) J.-C. Lin, K.C. Hsieh, R.C. Sharma, and Y.A. Chang The Pb-Te system is characterized by the existence of an intermediate phase, PbTe, with a very narrow range of homogeneity, which is formed at 50 at. % Te, and two eutectic reactions, one each in the Pb-PbTe and Pb Te-Te portions of the phase diagram. The eutectic in the Pb-PbTe region is very close to pure Pb. The assessed phase diagram is based primarily on the work of [02Fay], [15Kim], [39Gre], [65Lug], and [66Mil] and has been obtained by thermodynamic modeling. It was calculated by assuming the PbTe phase to be a line compound. Agreement between the calculated and the experimental phase diagram is good. The mutual solid solubilities of Pb and Te are limited. [39Gre] determined the solubility of Te in (Pb) to be 0.0065 at.% Te at 300 C. [65Lug] reported the solubility of Pb in (Te) to be 2.5 at.% Pb at 330 C, 1.5 at.% Pb at 260 C, and 0.85 at.% Pb at room temperature. The measurements of [65Lug] were not conducted under equilibrium conditions. Consequently, the present evaluators have assessed the solubility of Pb in (Te) to be negligible. PbTe is a semiconductor. It transforms from a cubic (NaCl-type) to an orthorhombic (GeS-type) structure at high pressures (41 kbar at room temperature). A two-phase region (cubic plus orthorhombic) has been reported between 50 to 80 kbar, and the volume change for the cubic to orthorhombic transformation was reported to be 5.2%. During crystallization studies of an amorphous 80 at.% Te alloy obtained by rapid cooling from the liquid phase, crystallization was reported to begin at ~64 C. The first phase to appear during crystallization had a hexagonal structure and may be considered a supersaturated solution of Pb in (Te). The liquidus in the Pb-PbTe region has an inflection point, which is indicative of a metastable liquid miscibility gap at lower temperatures. This miscibility gap calculation is based on a thermodynamic model and has not been confirmed experimentally. 02Fay: H. Fay and C.B. Gillson, Am. Chem. J., 27, 81-95 (1902). 15Kim: M. Kimura, Mem. Coll. Sci. Kyoto Univ., 1, 149-152 (1915) in German. 39Gre: J.N. Greenwood and H.W. Worner, J. Inst. Met., 115, 435-445 (1939). 65Lug: W. Lugscheider, H. Ebel, and G. Langer, Z. Metallkd., 56, 851-852 (1965) in German. 66Mil: E. Miller and K.L. Komarek, Trans. AIME, 236, 832-840 (1966). Published in Bull. Alloy Phase Diagrams, 10(4), Aug 1989. Complete evaluation contains 5 figures, 9 tables, and 49 references. Special Points of the Pb-Te System