Ionic and electronic properties of oxo-vanadium arsenate and phosphate frameworks

Electrically conducting zeolite-like frameworks are largely unstudied as electronic materials, but may offer new avenues in energy applications, ranging from electrical energy storage to catalysis. We present two zeolite-like framework materials, a vanadium arsenate [(As6V15O51)−9]∞, compound (1), and a vanadium phosphate [(P6V15O51)−9]∞, compound (2), their syntheses, and physical and electrical characterization. We compare the electrical characteristics of the two compounds through the measurements of conductivity as a function of temperature and extra-framework constituents. Our results indicate that compound (1) is a mixed conductor with framework electronic conduction and ionic conduction associated with the extra-framework constituents. Compound (2), in contrast, shows only ionic conductivity. Probing the electronic properties of zeolite-like mixed conductors paves the way for the innovative use of these materials.

Vanadium arsenate framework exhibiting mixed conductivity: crystal structure, variable temperature conductivity, and electron micrograph of a single crystal.Figure optionsDownload as PowerPoint slideHighlights
► Transition metal arsenate and phosphate frameworks.
► Electrical characterization.
► Mixed conductors, electronic plus ionic conduction pathways.
► Technological implications of zeolite-like mixed conductors.