Фазовая диаграмма системы Hg-Sm

К оглавлению: Другие диаграммы (Others phase diargams)

Hg-Sm (Mercury-Samarium) C. Guminski The assessed Sm-Hg phase diagram at constrained vapor pressure is hypothetical and is based on [Moffatt], who presumed similarity to the La-Hg and Pr-Hg partial phase diagrams. The increase in the thermal stability of Sm11Hg45 upon pressure was not taken into account because it was found by [66Kir] that the temperature of Sm11Hg45 decomposition was the same at either 1.33 x 104 or 1. 01 x 105 Pa. Formation of SmHg~6.5 was included into the assessed diagram [ 79Ian]; this phase seems to be stable at, or even below, room temperature. The temperature ranges of stability of SmHg, SmHg2, SmHg3, and Sm11Hg45 at normal pressure are drawn with solid lines. The equilibrium phases are (1) the liquid, a saturated solution of Sm in Hg on the liquidus line; (2) (aSm), (bSm), and (gSm), with maximum solid solubilities of a few percent at elevated temperature but decreasing below the XRD detectability level at ambient temperatures; (3) five intermetallic compounds, SmHg~6.5, Sm11Hg45, SmHg3, SmHg2, and SmHg, with narrow homogeneity ranges; and (4) (Hg), with very low solid solubility of Sm. The solid solubility of Hg in (Sm) in expected to increase to several atomic percent Hg in the temperature range 400 to 900 C by analogy to the Pr-Hg system. SmHg3 decomposed at 370 to 400 C at pressures of 1.33 x 104 and 1.01 x 105 Pa, respectively [66Kir, 67Lug]. SmHg2 was found to be stable up to 425 and 530 C (525 C in [67Lug]) at pressures of 1.33 x 104 and 1.01 x 105 Pa, respectively [66Kir]. SmHg was found to be the most stable Sm-Hg compound and decomposed at 500 and 630 C when Hg vapor pressure was 1.33 x 104 and 1.01 x 105 Pa, respectively [66Kir, 67Lug]. No compounds with Hg content lower than 50 at.% were detected in the Sm-Hg system [64Kir]. 58Ian: A. Iandelli, The Physical Chemistry of Metallic Solutions and Intermetallic Compounds, HMSO, London, Vol. 1, Paper 3F (1959). 64Kir: H.R. Kirchmayr, Acta Phys. Austr., 18, 193-204 (1964) in German. 66Kir: H.R. Kirchmayr and W. Lugscheider, Z. Metallkd., 57, 725-728 (1966) in German. 67Lug: W. Lugscheider, Ber. Bunsenges. Phys. Chem., 71, 228-235 (1967) in German. 68Ian: A. Iandelli and A. Palenzona, J. Less-Common Met., 15, 273-284 (1968). 79Ian: A. Iandelli and A. Palenzona, Handbook on the Physics and Chemistry of Rare Earths, K.A. Gschneidner and L. Eyring, Ed., North-Holland, Amsterdam, 1- 54 (1979). 79Mer: F. Merlo and M.L. Fornasini, J. Less-Common Met., 64, 221-231 (1979). Submitted to the APD Program. Complete evaluation contains 2 figures, 5 tables, and 26 references. Special Points of the Sm-Hg System