Defect chemistry of the cage compound, Ca(12)Al(14)O(33-delta)-understanding the route from a solid electrolyte to a semiconductor and electride.

A crystallographic cage structure endows mayenite (Ca(12)Al(14)O(33) or 12CaO.7Al(2)O(3); C(12)A(7)) with remarkable properties, making it either an oxygen solid electrolyte or an inorganic electride upon reduction. In order to better understand the transport properties of C(12)A(7), we measured the equilibrium total conductivity as well as the electronic partial conductivity of single crystal mayenite as functions of activity of oxygen or water vapor at different temperatures in the range 1073 < or =T/K < or = 1273.