Фазовая диаграмма системы Hg-Nd

К оглавлению: Другие диаграммы (Others phase diargams)

Hg-Nd (Mercury-Neodymium) C. Guminski The assessed Nd-Hg phase diagram, which is partly speculative, is based on that of [Moffatt], but the increase of Nd11Hg45 stability with pressure is not drawn as high as suggested in [Moffatt]. The temperature ranges of stability of NdHg, NdHg2, NdHg3, and Nd11Hg45 at normal pressure, which are shown as solid lines, are adopted from [66Kir]. The central portion of the diagram was constructed by analogy to the La-Hg and Pr-Hg systems at constrained pressure. [77Bul] prepared heterogeneous Nd amalgam by cementation of Nd(III) solution with sodium amalgam at ambient temperature. The solid phase, identified after the filtration of this amalgam, was found to be NdHg, instead of a compound richer in Hg, as would have been expected. Later, the NdHg transformed to a phase richer in Hg. This phenomenon is difficult to explain, because the Nd atom is surrounded permanently with at least five atoms of Hg in the liquid state. It has not been determined why NdHg first precipitates, then transforms with the addition of Hg. The possible formation of ternary Nd-Hg-H compounds was excluded by thermal analysis, chemical analysis, and infrared spectroscopy [77Bul]. Another phenomenon connected with metastability in the Nd-Hg system was described by [64Fla], who observed that the solid Nd amalgam at 1000 C still contained 19.4 at.% Hg. This observation is contradictory to the assessed phase diagram. No experimental details were reported by [64Fla], so the information should be treated cautiously. 64Fla: D.Flad and F. Matthes, Z. Chem., 4, 466 (1964) in German. 66Kir: H.R. Kirchmayr and W. Lugscheider, Z. Metallkd., 57, 725-728 (1966) in German. 77Bul: V.A. Bulina, A.I. Zebreva, and R. Sh. Enikeev, Izv. V.U.Z. Khim. Khim. Tekhnol., 20, 522-524 (1977) in Russian. Submitted to the APD Program. Complete evaluation contains 2 figures, 4 tables, and 20 references. 1