Dynamics of solid-state ion exchange between NH_4Cl and NaY

The steps of solid-state ion exchange between NH_4C1 and NaY has been put forward according to the theory of molecular surface diffusion and the dynamic models of solid-state ion exchange are derived theoretically.The experiment was done that mixture of NH_4Cl and NaY was ground and heated at certain temperature.The ion exchange degree was measured by ~(23)Na NMR.Three different ion exchange temperature points,100℃,15 0℃,and 200℃,were investigated and the relation between solid-state ion exchange degree and time was obtained, which derived the dynamic curve of solid-state ion exchange.This dynamic curve was fitted by preceding dynamic models of solid-state ion exchange.It was concluded that during the solid-state ion exchange between NH_4Cl and NaY,the reaction rate of the initial stage was controlled by the interface diffusion and after a while the rate was controlled by inner particle diffusion.