Фазовая диаграмма системы B-Er

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B-Er (Boron-Erbium) P.K. Liao and K.E. Spear Very little experimental data has been performed on the phase equilibria of the Er-B system. The assessed phase diagram is taken from [76Spe], which is primarily based on the phase information reported by [74Imp, 76Imp] and the boiling point data for Er metal from [Hultgren,E]. The liquidus curves of the Er-B system were largely estimated by [76Spe], and a 1-atm vapor phase is also included in the assessed diagram. In addition to the vapor, the equilibrium phases are (1) the liquid, L; (2) the terminal solid solution, cph (Er); (3) the terminal solid solution, rhombohedral (bB); and (4) four intermediate compounds, ErB2, ErB4, ErB12, and ErB66. Both (bB) and (Er) solid solutions have negligible composition ranges. The hexaborides are the most studied of the RE-boride phases and have been reported for all of the RE metals. However, the Er hexaboride appears to be unstable with respect to the other condensed phases in the Er-B system. The only uncertain melting temperature in the Er-B system is that of ErB4, which is estimated to be at 2500 C [76Spe]. The homogeneity ranges of Er borides are small except for ErB66. [73Nic] measured ErB66 phase boundary compositions to be ErB56с4 and ErB73с4. 59Eic: H.A. Eick and P.W. Gilles, J. Am. Chem. Soc., 81, 5030-5032 (1959). 62Lap: S.J. LaPlaca, Brookhaven National Laboratory, private communication ( 1962); quoted by [64Pos]. 64Pos: B. Post, Boron, Metallo-Boron Compounds, and Boranes, R.M. Adams, Ed., Interscience, New York, 301-371 (1964). 65Gie: R.F. Giese, Jr., J. Economy, and V.I. Matkovich, Z. Krist., 122, 144- 147 (1965). 70Car: J.-O. Carlsson and T. Lundstrom, J. Less-Common Met., 22, 317-320 (1970) . 72Cas: R.N. Castellano, Mater. Res. Bull., 7(4), 261-265 (1972). 72Fis: Z. Fisk, A.S. Cooper, P.H. Schmidt, and R.N. Castellano, Mater. Res. Bull., 7(4), 285-288 (1972). 72Sch: K. Schwetz, P. Ettmayer, R. Kieffer, and A. Lipp, J. Less-Common Met., 26, 99-104 (1972) in German. 72Spe: K.E. Spear and G.I. Solovyev, Solid State Chemistry, Proc. 5th Mater. Res. Symp., R.S. Roth and S.J. Schneider, Ed., NBS Spec. Publ. 364, Jul (1972). 73Nic: M.C. Nichols and R.W. Mar, Inorg. Chem., 12, 1710-1711 (1973). 74Imp: E.G. Imperato and K.E. Spear, presented at the 74th Ann. Meeting Am. Cer. Soc. (1972), and the 76th Ann. Meeting Am. Cer. Soc. (1974). 76Imp: E.G. Imperato, Ph.D. thesis in Solid State Science, The Pennsylvania State University, University Park, PA (1976). 76Spe: K.E. Spear, Phase Diagrams, Vol. 4, Materials Science and Technology, Academic Press, New York, 91-159 (1976). 77Cal: B. Callmer, Acta Crystallogr. B, 33, 1951-1954 (1977). 78Bea: B.J. Beaudry and K.A. Gschneidner, Jr., Handbook on the Physics and Chemistry of Rare Earths, Vol. 1, Metals, K.A. Gschneidner, Jr. and L. Eyring, Ed., North-Holland, Amsterdam, 215 (1978). Submitted to the APD Program. Complete evaluation contains 1 figure, 3 tables, and 27 references. Special Points of the Er-B System