To obtain Li3As and Li3Sb, a suspension of freshly powdered
As (or Sb) in anhydrous liquid NH3 is prepared. A solution of Li
in dried liquid ammonia is added, in small portions, to the suspension. The reaction begins on shaking. Its termination is indicated by the appearance of a blue color in the supernatant fluid,
due to a slight excess of Li. The NH3 is boiled out, with the last traces removed by vacuum. The products are either the brown
Li3As powder (very air sensitive; must be stored under pure N2 or
Ar) or blue-gray β-Li3Sb powder. The particle size of the latter
can be increased by heating at 650°C. Another modification, α-Li3Sb, is obtained by quenching of the melt (m.p. between 1150
and 1300°C) under Ar in a thick-walled iron crucible with welded-on
lid.
