Ion diffusion and mechanical losses in mixed alkali glasses

Maass, Philipp; Peibst, Robby

doi:10.1016/j.jnoncrysol.2005.12.061

Cited by 35 publications

(19 citation statements)

References 48 publications

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“…Figure 8(b) depicts normalized echo intensities recorded for all of the glasses at 348 K. In these glasses, F 2 decays to zero at long t m as expected by the stretched exponential function in Eq. (8). From this we find that the Li + ion dynamics are more than one order of magnitude faster in the x = 0.5 glass than either for the x = 0.0 or for the x = 1.0 glass.…”

Section: Dynamics Probed By Two-time Correlation Functionsmentioning

confidence: 60%

“…4,5 A generally accepted framework for the theoretical explanation of this century-old mixed-alkali effect 6,7 has emerged only recently. 8 With a perspective on battery applications 9 it is of course more interesting to identify materials for which glass component mixing leads to an enhancement rather than to a reduction of the ionic conductivity and other charge transport characteristics. In this context, mixed matrix glasses of the type yM 2 O + (1 -y)[xA + (1 -x)B], where A and B are glass formers which feature only a single type of mobile alkali ion M, are particularly interesting.…”

Section: Introductionmentioning

confidence: 99%

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NMR and conductivity studies of the mixed glass former effect in lithium borophosphate glasses

Storek

Böhmer

Martin

et al. 2012

The Journal of Chemical Physics

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Alkali ion charge transport has been studied in a series of mixed glass former lithium borophosphate glasses of composition 0.33Li 2 O + 0.67[xB 2 O 3 + (1 -x)P 2 O 5 ]. The entire concentration range, 0.0 ≤ x ≤ 1.0, from pure glassy Li 2 P 4 O 11 to pure glassy Li 2 B 4 O 7 has been examined while keeping the molar fraction of Li 2 O constant. Electrical conductivity measurements and nuclear magnetic resonance techniques such as spin relaxometry, line shape analysis, and stimulated-echo spectroscopy were used to examine the temperature and frequency dependence of the Li + ion motion over wide ranges of time scale and temperature. By accurately determining motional time scales and activation energies over the entire composition range the ion dynamics and the charge transport are found to be fastest if the borate and the phosphate fractions are similar. The nonlinear variation of the charge conduction, the most notable feature of the mixed glass former effect, is discussed in terms of the composition dependence of network former units which determine the local glass structure. Electrical conductivity measurements and nuclear magnetic resonance techniques such as spin relaxometry, line shape analysis, and stimulated-echo spectroscopy were used to examine the temperature and frequency dependence of the Li + ion motion over wide ranges of time scale and temperature. By accurately determining motional time scales and activation energies over the entire composition range the ion dynamics and the charge transport are found to be fastest if the borate and the phosphate fractions are similar. The nonlinear variation of the charge conduction, the most notable feature of the mixed glass former effect, is discussed in terms of the composition dependence of network former units which determine the local glass structure.

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Section: Dynamics Probed By Two-time Correlation Functionsmentioning

confidence: 60%

Section: Introductionmentioning

confidence: 99%

NMR and conductivity studies of the mixed glass former effect in lithium borophosphate glasses

Storek

Böhmer

Martin

et al. 2012

The Journal of Chemical Physics

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show abstract

“…MAE is a term that expresses a pronounced non-linearity of various physical and chemical properties when alkali ions of one type are continuously replaced with the unlike alkali ions. MAE can be observed by studying the dynamical properties as alkali diffusion [2,3], conductivity [4,5], but is also found for viscosity [6], chemical durability [7] and mechanical relaxation [8,9]. Hence, a strong correlation between unlike alkali ions must be present in alkali glass [10].…”

Section: Introductionmentioning

confidence: 99%

Mixed-alkali effect in sodium–potassium glasses irradiated with electrons

Gedeon

Jurek

Drbohlav

2010

Journal of Non-Crystalline Solids

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“…in Na 2 OSiO 2 melts. The conclusions of the studies of Day and Rindone (1962b) and Steinkamp et al (1967) have been confirmed by the modelling of Maass and Peibst (2006).…”

Section: Introductionmentioning

confidence: 57%

Shear modulus, heat capacity, viscosity and structural relaxation time of Na2O–Al2O3–SiO2 and Na2O–Fe2O3–Al2O3–SiO2 melts

Falenty

Webb

2010

Phys Chem Minerals

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The configurational heat capacity, shear modulus and shear viscosity of a series of Na 2 O-Fe 2 O 3 -Al 2 O 3 -SiO 2 melts have been determined as a function of composition. A change in composition dependence of each of the physical properties is observed as Na 2 O/(Na 2 O ? Al 2 O 3 ) is decreased, and the peralkaline melts become peraluminous and a new charge-balanced Al-structure appears in the melts. Of special interest are the frequency dependent (1 mHz-1 Hz) measurements of the shear modulus. These forced oscillation measurements determine the lifetimes of Si-O bonds and Na-O bonds in the melt. The lifetime of the Al-O bonds could not, however, be resolved from the mechanical spectrum. Therefore, it appears that the lifetime of Al-O bonds in these melts is similar to that of Si-O bonds with the Al-O relaxation peak being subsumed by the Si-O relaxation peak. The appearance of a new Al-structure in the peraluminous melts also cannot be resolved from the mechanical spectra, although a change in elastic shear modulus is determined as a function of composition. The structural shear-relaxation time of some of these melts is not that which is predicted by the Maxwell equation, but up to 1.5 orders of magnitude faster. Although the configurational heat capacity, density and shear modulus of the melts show a change in trend as a function of composition at the boundary between peralkaline and peraluminous, the deviation in relaxation time from the Maxwell equation occurs in the peralkaline regime. The measured relaxation times for both the very peralkaline melts and the peraluminous melts are identical with the calculated Maxwell relaxation time. As the Maxwell equation was created to describe the timescale of flow of a mono-structure material, a deviation from the prediction would indicate that the structure of the melt is too complex to be described by this simple flow equation. One possibility is that Al-rich channels form and then disappear with decreasing Si/Al, and that the flow is dominated by the lifetime of Si-O bonds in the Al-poor peralkaline melts, and by the lifetime of Al-O bonds in the relatively Si-poor peralkaline and peraluminous melts with a complex flow mechanism occurring in the mid-compositions. This anomalous deviation from the calculated relaxation time appears to be independent of the change in structure expected to occur at the peralkaline/peraluminous boundary due to the lack of charge-balancing cations for the Al-tetrahedra.

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Ion diffusion and mechanical losses in mixed alkali glasses

Cited by 35 publications

References 48 publications

NMR and conductivity studies of the mixed glass former effect in lithium borophosphate glasses

NMR and conductivity studies of the mixed glass former effect in lithium borophosphate glasses

Mixed-alkali effect in sodium–potassium glasses irradiated with electrons

Shear modulus, heat capacity, viscosity and structural relaxation time of Na2O–Al2O3–SiO2 and Na2O–Fe2O3–Al2O3–SiO2 melts

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