CN-mayenite Ca12Al14O32(CN)2: Replacing mobile oxygen ions by cyanide ions

Abstract

CN-mayenite (Ca12Al14O32(CN)2) is a promising candidate for high-temperature CN− conductivity in a solid due to its special structural features. It was prepared by a solid–gas reaction. The transport processes were investigated by means of in situ high-temperature neutron diffraction, impedance spectroscopy and additional Hebb–Wagner measurements. Diffusion pathways and activation energies were determined additionally by quantum-chemical calculations.Ca12Al14O32(CN)2 shows a surprisingly high ionic conductivity of σ = 1.4∙10−3 S/cm at 1173 K (Ea = 4.3 eV) and can be considered as first example of a new kind of solid anion conductor with a mobile molecular anion.