| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 73816 | Microporous and Mesoporous Materials | 2013 | 6 Pages |
The pressure-induced anomalously high AC conductivity of zeolite NaA mixed with water was measured by impedance spectroscopy at various water/zeolite ratios. The conductivity reaches a maximum value at 0.9–1.4 GPa with increasing water content of up to 20 wt.% in NaA + water. The high ionic conductivity of NaA compressed in water is interpreted to result from cation diffusion in the quasi-liquid Na+–H2O intra-channel system enhanced by the filling of additional H2O sites. The pressure range of anomalously high AC conductivity in NaA enlarges towards higher pressures with decrease of the water/zeolite ratio. An abrupt drop in conductivity observed at P > 1.5 GPa appears to be associated with freezing of intra-channel water. After pressure release, the overhydrated state of the zeolite kept in a closed container can be preserved for a long time, providing abnormally high conductivity which is comparable with that of Na+ β-alumina.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► We measured the electrical conductivity of hydrated NaA zeolite under high pressures. ► We added different amounts of additional water. ► The conductivity vs. pressure curves show anomalous increase then precipitous decrease. ► A mechanism is proposed for enhanced Na ion mobility via filling of additional H2O sites.
