Фазові рівноваги у потрійній системі Eu-Li-Sn за температури 400ºС

Abstract

The isothermal cross-section of the phase diagram of the system Eu-Li-Sn based on X-ray phase and local X-ray spectral analyses was constructed at the temperature 400ºС in the range 30-100 аt. % Sn. The alloys were prepared by arc melting of stoichiometric amounts of the constituent elements, annealed at 400ºС for 480 hours and quenched in cold water. The calculations and indexing powder diffraction were conducted using software LATCON and POWDER CELL-2.3. Calculations to refine the structure of the samples were carried out by means of programs CSD and 98 FullProf. Two new ternary compounds have been synthesized for the first time: EuLiSn2 (structural type CeNiSi2, Pearson symbol oS16, space group Cmcm, a = 0,4439(1), b = 1,8055(3), c = 0,4519(1) nm) and ~Eu4LiSn4 (unknown structure). The existence of the ternary compounds Eu5Li6Sn9, Eu5Li2Sn7, and EuLi8,71Sn6,29 and twelve binary phases was confirmed. Existence of the limited solid solution of inclusion based on the Eu5Sn3 binary compound Eu5LixSn3 (0 ≤ х ≤ 0,6) has been detected. Ultimate composition of this solid solution is Eu5Li0,6Sn3 (structural type Hf5CuSn3, Pearson symbol hP18, space group P63/mcm, a = 0,88134(3), c = 0,67785(2) nm). All these compounds have been refined using powder X-ray diffraction data (diffractometers DRON-2,0 (Fе Кα- radiation), STOE STADI P (Cu Kα1-radiation) and URD-6 (Cu Kα-radiation)). The characteristics of phase interactions in the Eu-Li-Sn as well as related systems with rare earth metals, Lithium and Tin have been analysed. Keywords: Еuropium; Lithium; Tin; ternary system; phase equilibria; synthesis; intermetallic compounds; crystal structure; solid solution.