A radiochemical method was used to examine the mobility of the Sr2+ and Ba2+ cations between high-energy sites in zeolite X. The results could be described by:

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

Sr:     D (m2/s) = 8 x 103exp[-127(kJ/mol)/RT]

The Mobility of Cations in Synthetic Zeolites with the Faujasite Framework - II. The Mobility of Calcium, Strontium and Barium Ions in Zeolite X at High Temperatures. A.Dyer, R.B.Gettins, R.P.Townsend: Journal of Inorganic and Nuclear Chemistry, 1970, 32[7], 2395–400