An investigation was made of H2O diffusion by making K2O additions. The latter reacted with the H2O, changed the colour of the crystal, and thereby indicated the depth of water penetration. It was found that the results, for 180 to 750C, could be described by:

D (cm2/s) = 7.7 x 100 exp[-0.69(eV)/kT]

C.Rühenbeck: Zeitschrift für Physik, 1967, 207[5], 446-69