Potassium and sodium self-diffusion in alkali feldspar

摘要: The rate of potassium self-diffusion in pure microcline was measured between 600° and 800° C using K40 as a tracer. Transport by processes other than volume diffusion insignificant or minimal. Isotropic coefficients were calculated assuming spherical grains. data are well fit the Arrhenius relation yield pre-exponential factor (D0) 133.8 cm2/sec an activation energy (Q) 70 kcal/mole. Similar experiments on Na22 low-albite (exchanged microcline) D0 2.31×10−6 Q approximately 19 kcal/mole for temperature interval from 200° to C. large difference these energies suggests that atomic mechanisms sodium different.