Recent Developments in Nitride Chemistry

Abstract

The chemistry of ternary nitrides is reviewed with special focus on developments of the last two years (1996 and 1997). In particular, structures and properties of ternary and higher transition metal nitrides, main group nitrides, subnitrides, and nitride halides are compared, and a section on thermodynamics of ternary nitrides is included. Finally, methods for the preparation of gallium nitride single crystals are summarized.

First-principles electronic structure calculations of Ba5Si2N6 with anomalous Si2N6 dimeric units

“…The interaction between the semicore-level states Ba 5p and N 2s is significant. Finally the compound is calculated to be a semiconductor with an indirect gap of [1] 0.7 eV. Last years a number of new alkaline-earth silicon Sr, Ba) compounds [6,7].…”

Structural Classification of Quasi-One-Dimensional Ternary Nitrides

“…This electropositive element is usually an alkali, alkaline earth, or lanthanide metal. The second metal is commonly a transition metal, which has a tendency to form nitridometalate anions, MN x n− [38]. The coordination and connectivity of the nitridometalate anions dictates the main structural characteristics of the nitrides and influences the physical properties.…”

“…The coordination and connectivity of the nitridometalate anions dictates the main structural characteristics of the nitrides and influences the physical properties. In general, the early transition metals, in ternary nitrides, tend to favour relatively high oxidation states and high coordination numbers (4)(5)(6), while the late transition metals show lower oxidation states (0-2), and lower coordination [38]. Below are several of the better-known nitride systems, addressed in terms of their coordination of the metal nitrides.…”

“…In general, the ternary nitrides in which the transition metal (TM) shows high coordination numbers (5 or 6) with nitrogen tend to form rocksalt, perovskite, or layered structures and are commonly considered to contain TM-N polyhedra [38]. However, many subnitrides, containing a high metal-to-nitrogen ratio, contain chains of octahedra and are commonly described in terms of the nitrogen coordination.…”

“…Compounds with a full range of structural features, from isolated tetrahedra to complex three-dimensional networks, are known to occur [38]. The following structures show chains of metal-centred nitrogen tetrahedra, showing either edge or corner connectivity.…”