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Pressure dependence of ionic conductivity of hydrated and dehydrated zeolites A |
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| Authors: | SV Goryainov RA Secco Y Huang H Liu |
| Institution: | aDepartment of Earth Sciences, University of Western Ontario, London, Ontario, Canada N6A 5B7 bCentre for Chemical Physics, University of Western Ontario, London, Ontario, Canada N6A 3K7 cDepartment of Chemistry, University of Western Ontario, London, Ontario, Canada N6A 5B7 dInstitute of Geology and Mineralogy, pr. Ac. Koptyuga 3, Novosibirsk, 630090, Russia |
| Abstract: | Hydrated and dehydrated zeolites MA (where M=Li, Na and K) with LTA structure have been studied by impedance spectroscopy with scanning frequency from 1 Hz to 1 MHz at high pressure up to 4.5 GPa and high temperature up to 250 °C. Anomalous increase in electrical AC conductivity at about 1.5–2 GPa observed in hydrated zeolites is associated with changes in crystalline structure leading to the formation of high-diffusion state of cation and water stuffing of the channels. In dehydrated zeolites, electrical conductivity is controlled by diffusion of cations (Li+, Na+ and K+), which is determined by cation sites and aluminosilicate ring windows. LiA and NaA zeolites show normal decrease of conductivity with pressure, whereas KA zeolite exhibits the anomalous dependence with considerable increase and then fast decrease of conductivity. The behaviour of KA zeolite is associated with nearly central location of cation site in 8-membered ring, different from that in LiA and NaA zeolites. |
| Keywords: | Amorphous materials Micro-porous materials High pressure Electrical conductivity Phase transitions Zeolite A |
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