Effect of solvation of charge carriers in hydrated zeolites

Mogensen, Naja

doi:10.1016/0167-2738(94)00258-t

Cited by 15 publications

(4 citation statements)

References 2 publications

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“…This is shown in Figure 11 for the three chabazites, with each exhibit distinct slope = -E a /k B . The activation energy (E a ) was observed to decrease at lower temperatures (<200 °C) and can be attributed to partial rehydration of the chabazites at low temperature; this behaviour has been observed by Mogensen and Skou [49]. and in Figure 8.…”

Section: Electrical Properties During Coolingsupporting

confidence: 58%

Understanding the AC conductivity and permittivity of trapdoor chabazites for future development of next-generation gas sensors

Bordeneuve

Wales

Physick

et al. 2018

Microporous and Mesoporous Materials

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Synthetic K + chabazite (KCHA), Cs + chabazite (CsCHA) and Zn 2+ chabazite (ZnCHA) have been synthesized and investigated in order to relate the differences in their crystalline structures to their thermal stability, moisture content and frequency dependent alternating current (AC) conductivity, permittivity and phase angle at a range of temperatures. The materials are shown to exhibit the universal dielectric response, which is typical of materials consisting of both conductive and insulating regions. Due to the presence of porosity the three chabazites were hydrated significantly at room temperature and so the dehydrated state was achieved by heating the chabazites to high temperatures to ensure that all different energetic types of water were removed. Cation migration activation energies for KCHA (0.66 ± 0.10) eV, CsCHA (0.88 ± 0.01) eV and ZnCHA (0.90 ± 0.01) eV were determined during the cooling cycle from the fully dehydrated state to provide an accurate measurement the activation energies. Good thermal stability of the materials was observed up to 710 °C and below 200 °C the electrical properties can be strongly influenced by hydration level. Overall, it was determined that when either hydrated or dehydrated, KCHA had the highest conductivity and lowest cation migration activation energy of the three studied chabazites and thus has the most promising electrical properties for potential use as a gas sensing material in next-generation electrical-based gas sensors.

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Section: Electrical Properties During Coolingsupporting

confidence: 58%

Understanding the AC conductivity and permittivity of trapdoor chabazites for future development of next-generation gas sensors

Bordeneuve

Wales

Physick

et al. 2018

Microporous and Mesoporous Materials

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“…The mechanism of electrical conduction in a zeolite has been the subject of several studies. Conduction of dehydrated potassium zeolite L has been found to involve a thermally activated process. , Dielectric properties of the zeolites depend on the degree of hydration . The zeolites can act as a host for a large number of guest molecules.…”

Section: Zeolitementioning

confidence: 99%

Dielectric Relaxation and Solvation Dynamics of Water in Complex Chemical and Biological Systems

2000

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“…The dielectric properties of these solids have also been studied when gas adsorption is involved, particularly in the case of water vapor. − The electrical conductivity of dehydrated zeolites is generally ascribed to exchangeable cations, ,,− and attempts of modeling have been proposed. For example Tabourier et al developed a model based on the existence of correlated motion of cations in a “cluster”, but there is no complete satisfying model explaining the hopping mechanism.…”

Section: Introductionmentioning

confidence: 99%

“…Several interrogations still remain in the study of hydrated or partially hydrated zeolites related to the nature of the carriers responsible for the hopping conductivity. According to some authors, ,, the water molecules can increase the mobility of extraframework cations, while others attribute part of the increase of conductivity to the protons due to the water. , However, zeolites are very complex systems and their properties depend on several parameters such as (1) the chemical composition that gives the ratio Si/Al, (2) the type of exchangeable cations, (3) the hydration state or the outgassing temperature, and (4) the measuring temperature. All these parameters affect the distribution of the exchangeable cations on the different sites of the zeolites.…”

Section: Introductionmentioning

confidence: 99%

Dielectric Properties of a Faujasite Y as a Function of the Hydration State

et al. 1997

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The evolution of conduction and polarization phenomena is studied as a function of dehydration temperature (TT varying from 100 up to 400 °C) on a faujasite Y zeolite. The measurements are carried out as a function of frequency at different temperatures. In all cases, the conductivity is ascribed to the migration of cations in large cages involving energies varying from 0.61 to 0.85 eV. Two relaxation domains are observed. It is assumed that they are due to the movement of cations of sites III‘ and II. The existence of these two domains is confirmed by the technique of the thermally stimulated currents. The spreading domain of relaxation depends on the dehydration state of the zeolite.

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Effect of solvation of charge carriers in hydrated zeolites

Cited by 15 publications

References 2 publications

Understanding the AC conductivity and permittivity of trapdoor chabazites for future development of next-generation gas sensors

Understanding the AC conductivity and permittivity of trapdoor chabazites for future development of next-generation gas sensors

Dielectric Relaxation and Solvation Dynamics of Water in Complex Chemical and Biological Systems

Dielectric Properties of a Faujasite Y as a Function of the Hydration State

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