THERMOCHEMISTRY OF METAL NITRIDES IN THE CA ZN/N SYSTEM/

The energetics of ternary oxide formation is reasonably well understoo d, but little is known of the energetics of ternary nitride formation. We have developed new procedures for high-temperature oxide melt solu tion calorimetry on metal nitrides and employed them to study compound s in the Ca/Zn/N system. The calorimetry utilized the easy reduction o f MoO3 in the solvent to supply a pathway for rapid oxidation of ''N3- '' to N-2 gas. These experiments represent the first high-temperature solution calorimetry of ternary metal nitrides. The results indicate t hat Ca3N2 acts as a basic nitride analogous to CaO in oxide systems, w hile Zn3N2 acts as an acidic nitride (''N3-'' acceptor) in this ternar y nitride system.