ISOTHERMAL SECTION OF STATE DIAGRAM Ce–Lі–Sn SYSTEM IN THE 30-100 AT. % Sn CONCENTRATION RANGE AT 400ºС

Abstract

The isothermal cross-section of the phase diagram of the system Ce–Li–Sn based on X-ray phase and local X-ray spectral analyses was constructed at the temperature 400ºС in the 30–100 аt. % Sn concentration range. 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.
 Flame photometer Flapho-4 was used for the experimental determination of lithium amount. To confirm the phase composition of some system samples energy-dispersive X-ray spectroscopy method (EDX) was used (scanning electron microscope REMMA-102-02).
 The calculations and indexing of diffraction powder patterns (diffractometers DRON-2,0 (Fе Кα-radiation), STOE STADI P (Cu Kα1-radiation) and URD-6 (Cu Kα-radiation)) have been conducted using LATCON and POWDER CELL-2.3 software. Calculations to refine the structure of samples have been carried out by with WinCSD and FullProf 98 programs.
 Two new ternary compounds have been synthesized for the first time: Ce5Li6Sn9 (structure type Eu5Li6Sn9, Pearson symbol oS80, space group Cmcm, a = 0,4852(1), b = 2,8961(4), c = 1,5009(2) nm) and ~Ce4LiSn4 (unknown structure). The existence of the ternary compounds CeLiSn2 (structural type CeNiSi2), Ce5Li2Sn7 (own structure type) and fifteen binary phases was confirmed. The existence of the limited solid solution of inclusion Ce5LixSn3 (0 ≤ х ≤ 0,5) based on the Сe5Sn3 binary compound has been detected. The ultimate composition of this solid solution is Ce5Li0,5Sn3 (structure type Hf5CuSn3, Pearson symbol hP18, space group P63/mcm, a = 0,88206(2), c =0,67802(1) nm).
 The existence of the binary and ternary phases CeSn3, Ce5Sn3, Ce5Sn4, Ce11Sn10, Ce3Sn5, Ce3Sn7, Ce2Sn5, Ce3Sn, Li17Sn4, Li7Sn2, Li13Sn5, Li5Sn2, Li7Sn3, LiSn, Li2Sn5, CeLiSn2, Ce5Li2Sn7 was confirmed.
 The characteristics of phase interactions in the Ce–Li–Sn as well as related ternary systems with rare earth metals, Lithium, Silicon, Germanium and Tin have been analysed.