A technique was used in which H2O was diffused into the halide. The formation of H2 then occurred within the crystal, according to:

2K + 2H2O → 2KOH + H2

The resultant H2 diffused partly into the crystal to form a KH layer:

½H2 + K → KH

The H2O also reacted with the KH to form a KOH layer:

H2O + KH → KOH + H2

The H2 diffusion coefficient could then be deduced from measurements of the growth kinetics of the KH and KOH layers. The results for temperatures ranging from 180 to 420C could be described by:

D (cm2/s) = 630 exp[-0.97(eV)/kT]

New Method for the Determination of the Diffusion Coefficient of H in Alkali Halides. H.Gruendig, C.Rühenbeck: Zeitschrift für Physik, 1972, 249[3], 269-78