Niobium Oxyiodide Clusters from Heterogeneous Solid-State Reactions: The Example Li 3 Nb 7 O 5 I 14 (NbI 6 )

Abstract

No fewer than nine niobium oxyiodide phases have been synthesised and characterised from the reaction between NbI4 and Li2O in the presence of Li2(CN2) under closed-system conditions at temperatures between 400 °C and 500 °C. Reactions in this system proceed through diffusion-controlled solid-solid pathways as well as gas-phase reactions that extend beyond equilibrium, that enables the concurrent formation of multiple niobium oxyiodide compounds. The crystal structures of these products display a range of architectures based on different niobium oxide clusters, including the [Nb7O5] core, which is a characteristic structural motif in the structure of Li3Nb7O5I14(NbI6), the compound examined in this report.