Фазовая диаграмма системы Ag-P

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Ag-P (Silver-Phosphorus) I. Karakaya and W.T. Thompson The phase diagram for the Ag-P system is not well established. The assessed equilibrium diagram at standard atmospheric pressure is quite different from [ Hansen], but is topologically similar to [Elliott]. Because white P boils at 280 C at standard atmospheric pressure, the vapor field G is also included in the equilibrium diagram. The proposed diagram is based mainly on a thermodynamic model developed from the available experimental data [32Har, 32Mos, 59Urb, 59Vog, 65Olo, 81Mol]. Because white P is the common form of elemental P, it generally is taken to be the standard state, although red P may in fact be more stable at 25 C and standard atmospheric pressure [77Bar, 68Wag]. For this reason, the sublimation temperature of solid red P at standard atmospheric pressure is indicated in the assessed diagram. The solid solubility of P in (Ag) is less than 0.07 at.% [32Mos]. Decomposition of Ag3P11 takes place at 458 C. The solid compounds Ag2P3 and AgP are believed to be metastable over the range of temperatures shown in the assessed diagram. The formula "AgP3" found in some publications [77Bar] is interpreted in this evaluation as an erroneous reference to the compound Ag3P11, because [81Mol] reported that "AgP3" is in a two-phase region. As can be seen in the assessed diagram, the small field for the liquid phase and the very small P solubility in solid (Ag) make it particularly amenable to thermodynamic modeling. The assessed phase diagram agrees with the experimental data [32Mos, 59Vog] that the temperature of the invariant reaction is near 880 C; however, experimental findings of the P solubility in liquid Ag [59Vog] are found to be incorrect. Moreover, the placement of Ag- rich liquidus in the assessed diagram cannot be altered very much, because it is determined by the partial thermodynamic properties of Ag, and these properties are close to the ideal value for these concentrations. 32Har: H. Haraldsen, Skr. Norske Videnskaps-Akad. Oslo, 9, 1-63 (1932) in German. 32Mos: H. Moser, K.W. Fr”hlich, and E. Raub, Z. Anorg. Chem., 208, 225-237 ( 1932) in German. 59Urb: G. Urbain and L.D. Lucas, Compt. Rend., 248, 230-233 (1959) in French. 59Vog: R. Vogel, R. Dobbener, and O. Strathmann, Z. Metallkd., 50, 130-135 ( 1959) in German. 65Olo: O. Olofsson, Acta Chem. Scand., 19, 229-241 (1965). 68Wag: D.D. Wagman, W.H. Evans, V.B. Parker, I. Halow, S.M. Bailey, and R.H. Schumm, Selected Values of Chemical Thermodynamic Properties, National Bureau of Standards Series 270-3, U.S. Department of Commerce, Washington, DC (1968). 77Bar: I. Barin, O. Knacke, and O. Kubaschewski, Thermodynamic Properties of Inorganic Substances (Supplement), Springer-Verlag, Berlin (1977). 81Mol: M.H. Moller and W. Jeitschko, Inorg. Chem., 20, 828-833 (1981). Published in Bull. Alloy Phase Diagrams, 9(3), Jun 1988. Complete evaluation contains 5 figures, 4 tables, and 17 references. Special Points of the Ag-P System