Oxygen transport in undoped and doped mayenite

We report a comparative study of oxygen transport in one nominally undoped, one iron-doped and one nickel doped sample of the calcium aluminate cage-compound mayenite. A single gas-phase O-18/O-16 exchange was performed at a temperature of T = 1223 K and at an oxygen activity of aO(2) = 0.1 for all three samples. Isotope profiles were determined subsequently by means of time-of-flight secondary ion mass spectrometry (ToF-SIMS). Analysis of the profiles yielded oxygen tracer diffusion coefficients D-O* and oxygen surface exchange coefficients k(O)*. Within experimental error, cation doping did not produce any changes in D-O* or k(O)*. (C) 2015 Elsevier B.V. All rights reserved.