Lithium nitride, Li₃N

The nitride is best prepared by the action of nitrogen on the metal at ordinary temperatures, the product being a grey, amorphous, hygroscopic substance, unaffected by dry hydrogen or air, but rapidly decomposed by moisture. It absorbs both nitrogen and oxygen from the air. A ruby-red, crystalline modification is formed by the action of lithium on nitrogen at 450° to 460° C. It is less hygroscopic than the amorphous form, and does not absorb gases in the cold. At 840° to 845° C. in a current of nitrogen the amorphous nitride becomes crystalline. Water decomposes the nitride according to the equation

Li₃N+3H₂O = 3LiOH+NH₃.

Guntz recommends the formation of the nitride as a convenient means of isolating argon, and its interaction with metallic chlorides as a method for preparing other nitrides. For the heat of formation he found 49.5 Cal. It is formed by the action of light on lithium imide, Li₂NH:

2Li₂NH ⇔ Li₃N+LiNH₂.