Thermally Activated Motion of Sodium Cations in Insulating Parent Low-Silica X Zeolite

TL;DR

This study investigates the thermally activated motion of sodium cations in insulating low-silica X zeolite using $^{23}$Na NMR relaxation rates, revealing low activation energy and short-distance jumps within supercages.

Contribution

It provides new insights into sodium cation dynamics in low-silica X zeolite, highlighting lower activation energy and localized jumps compared to heavily loaded samples.

Findings

Activation energy of 15 meV for sodium motion

Multiple BPP-type relaxation behavior observed

Short-distance jumps within supercages identified

Abstract

We report a $^{23}$Na spin-lattice relaxation rate, $T_1^{-1}$, in low-silica X zeolite. $T_1^{-1}$ follows multiple BPP-type behavior as a result of thermal motion of sodium cations in insulating material. The estimated lowest activation energy of 15~meV is much lower than 100~meV observed previously for sodium motion in heavily Na-loaded samples and is most likely attributed to short-distance jumps of sodium cations between sites within the same supercage.