A radiochemical method was used to examine the mobility of Ba2+ cations between high-energy sites in zeolite X. The results could be described by:

D (m2/s) = 5 x 10-1exp[-66(kJ/mol)/RT]

A.Dyer, R.B.Gettins, R.P.Townsend: Journal of Inorganic and Nuclear Chemistry, 1970, 32[7], 2395–400