Morphology and Conductivity of Copper Hexacyanoferrate Films

Films of conductive coordination network com-pounds are interesting as functional materials for charge storage, electrocatalysis, electrochromic switching, or conversion of light. The electrical conductivity depends on not only intrinsic material properties but also grain boundaries. Copper hexacyanoferrate shows a remarkable variation in film morphologies depending on the preparation route. Conductive films can only be obtained for continuous crystalline films that have been received by a combination of sonication-assisted casting and vapor-assisted conversion. Electrical conductivities of these films are higher than those of powder pellets with a similar crystal structure. Temperature-dependent and humidity-dependent measurements on powder pellets revealed the activation energies for charge transport. Thermogravimetric analysis, temperature-dependent X-ray diffraction data, and humidity-dependent measurements on powder pellets revealed the activation energies for charge transport and the role of proton conductivity.