Thermodynamics of nitride and hydride formation by the reaction of metals with flowing NH 3

Abstract

The state where the equilibrium dissociation of ammonia, NH 3 = − 1 2 N 2 + 3 2 H 2 , is not reached can be produced by flowing NH 3. In this case NH 3 must be considered to be in an unstable state. Nitrogen-rich metal nitrides, which cannot be obtained by action of N 2 under normal pressures, can be prepared by use of a stream of NH 3. This suggests that high nitrogen activity may arise from the high instability exhibited by a stream of NH 3. It may be highly probable that a stream of NH 3 also acts as a hydriding agent with high hydrogen activity. A thermodynamic analysis was performed with the object of gaining insights into these aspects from the equilibrium point of view.