Thermochemistry of metal nitrides in the Ca/Zn/N system

The energetics of ternary oxide formation is reasonably well understood, but little is known of the energetics of ternary nitride formation. We have developed new procedures for high-temperature oxide melt solution calorimetry on metal nitrides and employed them to study compounds in the Ca/Zn/N system. The calorimetry utilized the easy reduction of MoO₃ in the solvent to supply a pathway for rapid oxidation of "N^3-" to N ₂ gas. These experiments represent the first high-temperature solution calorimetry of ternary metal nitrides. The results indicate that Ca₃N₂ acts as a basic nitride analogous to CaO in oxide systems, while Zn₃N₂ acts as an acidic nitride ("N^3-" acceptor) in this ternary nitride system.