Lithium dynamics in the zeolite-like lithosilicate RUB-29 and its high-temperature structure after dehydration (Cs14Li42Si72O172)

Abstract

The thermally induced modifications of the zeolite-like lithosilicate In particular, extra-framework Li cations located within porous 8-and 10-membered ring-channels, where these Li cations were partially coordinated with zeolitic water in the original structure, migrate into densely packed Li 2 O-layers after dehydration. As a result of the migration, the number of empty sites relevant for Li hopping in Li 2 O-layers decreases, which give a negative effect on the long-range charge transfer in dehydrated RUB-29. Its DC conductivity values estimated from AC impedance spectra lie between 2 · 10 À5 and 6 · 10 À5 S cm À1 at 873 K, and a low activation energy of 51 kJ/mol (ffi 0.53 eV) could be determined for the bulk charge transfer process in dehydrated RUB-29.Li