It was found that the data for 950 to 1150C could be described by:

D (cm2/s) = 6.8 x 10-2 exp[-15.9(kcal/mol)/RT]

J.Besson, C.Deportes, R.Schmitt, G.Danger: Bulletin de la Société Chimique de France, 1966, 11, 3394-8