Uranium Nitrides

It was observed by Moissan that uranium metal combined directly with nitrogen at 1000° C., yielding a yellow nitride the composition of which has not been ascertained. By heating uranous chloride in a stream of dry ammonia, or by heating to redness the double chloride Na₂UCl₆ in a current of ammonia, a greyish-black crystalline nitride, of composition U₃N₄, is obtained. It is probable that this compound is frequently present in metallic uranium, for the latter when exposed to kathode rays has been observed to evolve a little nitrogen. It has been suggested that the activity of uranium carbide as a catalyst in the synthesis of ammonia from nitrogen and hydrogen depends on nitride formation.

When uranyl chloride is heated in ammonia a product of uncertain composition, probably an oxynitride, is obtained.