A revised view on the mixed-alkali effect in alkali borate glasses

Imre, Árpád W.; Divinski, Sergiy V.; Voß, S.; Berkemeier, Frank; Mehrer, H.

doi:10.1016/j.jnoncrysol.2006.02.008

Cited by 31 publications

(16 citation statements)

References 34 publications

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“…Above x = 0.55 the increase in NaPSS content is then accompanied by a much stronger increase of σ dc and decrease of ΔH dc , respectively. The strong increase of σ dc with x is reminiscent of inorganic glasses in which the dc conductivity increases with the number density of mobile ions in a power-law fashion [40][41][42][43]. The latter finding is attributed to a strong increase in ion mobility [40].…”

Section: Conductivities Of Pecmentioning

confidence: 95%

Mechanisms of Ion Conduction in Polyelectrolyte Multilayers and Complexes

Schönhoff¹,

Imre

Bhide

et al. 2010

Zeitschrift Für Physikalische Chemie

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This paper reviews the progress made in understanding of the mechanisms of ion conduction in polyelectrolyte multilayers (PEM) and polyelectrolyte complexes (PEC). The basis are experimental conductivity data obtained by impedance spectroscopy as a function of relative humidity and temperature, respectively. Mechanically stable thin films of PEM have interesting perspectives as ion conductors, however, being prepared by self-assembly, their stoichiometry and content of ionic charge carriers is unknown. Therefore PEC act as a model material with a variable stoichiometry and known ion content.Employing poly(sodium 4-styrene sulfonate) (NaPSS) and poly(diallyldimethyl ammoniumchloride) (PDADMAC), we present conductivity spectra of dried polyelectrolyte complexes of type x NaPSS · (1 − x)PDADMAC as a function of temperature and composition, respectively. The dependence of the dc conductivity is discussed along with scaling properties of the spectra. The results show that the conductivity is always determined by the sodium ions, even in PEC with an excess of PDADMAC. The ion dynamics and transport mechanisms are, however, different in PDADMAC-rich than in NaPSS-rich PEC.PEM of different polyionic compounds are investigated in dependence on relative humidity. A general law of an exponential increase of the dc conductivity with relative humidity is found. Absolute values of the conductivity and the strength of the humidity dependence are different for different polyion materials, however, they do not depend on the type of small counterion employed in layer formation. Therefore, it is concluded that in hydrated PEM, protons are the dominant charge carriers.For both PEM and PEC we show that the MIGRATION concept developed by Funke and co-workers can be used for describing the experimental spectra over wide ranges in frequency. This implies that forward-backward hopping motions of small ions play a vital role in solid polyelectrolyte materials. Apart from these potentially successful hops, localized motions of charged particles are found to influence the conductivity spectra as well.

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Section: Conductivities Of Pecmentioning

confidence: 95%

Mechanisms of Ion Conduction in Polyelectrolyte Multilayers and Complexes

Schönhoff¹,

Imre

Bhide

et al. 2010

Zeitschrift Für Physikalische Chemie

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“…A new subnetwork diffusion concept to this novel view on the mixedalkali effect is in preparation [29]. Fig.…”

Section: Comparison Of Single and Mixed-alkali Glassesmentioning

confidence: 99%

Molar volume, glass-transition temperature, and ionic conductivity of Na- and Rb-borate glasses in comparison with mixed Na–Rb borate glasses

Berkemeier

Voß

Imre

et al. 2005

Journal of Non-Crystalline Solids

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100

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“…Thus, the collectivity of ion jumps is a necessary and probably also a sufficient condition for power-law like r dc (X) behavior in Na borate glasses and for the mixed-alkali effect in Na-Rb borate glasses. Elsewhere it have been suggested that the existence of the mixed-alkali effect also depends on the presence of collectively moving ions in single and mixed cation glasses [17,18].…”

Section: Discussionmentioning

confidence: 99%