Solubilities of silicon and of germanium in liquid lithium. Lithium–germanium partial phase diagram

Abstract

The solubilities of silicon (0.00 ⩽x_Si⩽ 0.0165) and of germanium (0.00 ⩽x_Ge⩽ 0.0872) in liquid lithium have been determined by equilibrium resistivity methods and can be represented, in part, by the equations ln x_Si= 5.548 – 6775/T 500 ⩽T/K ⩽ 700 ln x_Ge= 5.459 – 6630/T 530 ⩽T/K ⩽ 715. A thermochemical cycle is used to derive solvation enthalpies (for the neutral gaseous species) for silicon (–557 kJ mol^–1) and for germanium (–490 kJ mol^–1) in liquid lithium. The compounds Li₂₂Si₅ and Li₂₂Ge₅ have been shown to precipitate from dilute solutions of silicon and of germanium in liquid lithium, respectively. The melting point of Li₂₂Ge₅(934 K) and the lithium-rich eutectic horizontal (453.5 K) of the lithium–germanium system have been established by d.t.a. and t.a. techniques, respectively. These results, together with the solubility data, have been used to augment the lithium–germanium phase diagram (0.00 ⩽x_Ge⩽ 0.20).