Transition metal-based double nitrides

Abstract

This paper reviews the formation of several transition metal based double nitrides. The metallic nature of the nitrides has been used as the basis for understanding their properties and structure. At 3 GPa and 1673 K normally covalent GaN with a wurtzite structure reacts with NbN to form cubic (Nb1−x Ga x )N solid solutions (x ⩽ 0.15). Ga was found in a distorted octahedral environment. In reactions with nitrogen at 1273 K, alkaline earth metals (A) formed stoichiometric compounds of ANiN with nickel and A3MN3 with metals (M = V, Cr, Fe, Co). These compounds had [NiN]2− infinite linear chains and [MN3]6− trigonal planar units. Covalent nature was very important in understanding the bonding between M and N in these alkaline earth transition metal nitrides. The type of structural unit depended on the number of d-electrons. Rf-sputter deposition as well as high pressure synthesis was useful for preparing metastable transition metal nitrides and their solid solutions. (Ti1−x Al x )N solid solutions and a new compound FeN with zinc blende type structure were obtained by rf-sputtering.