Фазовая диаграмма системы Ge-La

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Ge-La

Ge-La (Germanium-Lanthanum) A.B. Gokhale and G.J. Abbaschian The assessed La-Ge phase diagram is based primarily on the work of [71Ere] and [72Ere]. Other data pertaining to the phase equilibria in the 60 to 70 at.% Ge range are conflicting. There is sufficient evidence to indicate the presence of only one intermediate phase in this composition range, shown as LaGe2-x in the assessed diagram. Therefore, the data for LaGe2 are ascribed to LaGe2-x in this assessment. [71Ere] and [72Ere] determined the liquidus reliability, and it is indicated as such in the assessed diagram. The mixing process in the liquid is exothermic, with a strong negative deviation from ideality. The solid solubility of Ge in (La) has not been determined, but is probably very small. [71Ere] found two phases in a 98 at.% Ge alloy at the eutectic temperature of 810 C and concluded that the maximum solid solubility of La in (Ge) is less than 2 at.%. LaGe [66Bus] and La5Ge3 [67Bus, 83Kre] are Pauli paramagnetic. [66Oht] noted a superconducting transition temperature (TC) and Debye temperature (qD) for LaGe2-x (LaGe2) of 2.2 and 222 K, respectively, whereas according to [77Gho1] and [77Gho2], this phase becomes superconducting at 2.6 K. [77Gho2] further noted that La5Ge3 does not exhibit a superconducting transition down to 1.6 K. 64Gla1: E.I. Gladyshevskii, Zh. Strukt. Khim., 5, 568-575 (1964) in Russian; TR: J. Struct. Chem., 5, 523-529 (1964). 64Gla2: E.I. Gladyshevskii, Zh. Strukt. Khim., 5, 919-921 (1964) in Russian; TR: J. Struct. Chem., 5, 852-853 (1964). 66Bus: K.H.J. Buschow and J.F. Fast, Phys. Status Solidi, 16, 467-473 (1966). 66Oht: T. Ohtsuka and T. Satoh, Ann. Acad. Sci. Fennicae A, VI, 210(40), 92-97 (1966). 67Bus: K.H.J. Buschow and J.F. Fast, Phys. Status Solidi, 16, 467-473 (1966). 71Ere: V.N. Eremenko, Z.K. Shi, Yu.I. Buyanov, and V.G. Batalin, Porosh. Metall., 11(8), 82-86 (1971) in Russian; TR: Sov. Powder Metall. Met. Ceram., 10, 661-664 (1971). 72Ere: V.N. Eremenko, Z.K. Shi, Yu.I. Buyanov, and A.M. Kharkova, Dop. Akad. Nauk Ukr. RSR, (9), 819-823 (1972) in Ukrainian. 77Gho1: A.K. Ghosh and D.H. Douglass, Solid State Commun., 23(4), 223-226 ( 1977). 77Gho2: A.K. Ghosh and D.H. Douglass, J. Low Temp. Phys., 27(3-4), 487-512 ( 1977). 82Kre: R.P. Krentsis, S.M. Barmin, A.A. Sevast›yanov, and P.V. Gel›d, Fiz. Tverd. Tela, 24, 2856-2859 (1982) in Russian; TR: Sov. Phys. Solid State, 24(9) , 1620-1621 (1982). Published in Bull. Alloy Phase Diagrams, 10(4), Aug 1989. Complete evaluation contains 3 figures, 3 tables, and 32 references. Special Points of the La-Ge System