Evidence for site memory effects in the ionic relaxation of (Li2O)x(Na2O)y(GeO2)1-x-y glasses

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Abstract

We report measurements of the dielectric response due to ionic relaxation in alkali germanate glasses (Li2O)x(Na2O)y(GeO2)1-x-y. The relaxation is investigated in both electric modulus and ac conductivity formalisms, between which important discrepancies are observed. In single alkali glasses, the width of the electric modulus decreases with decreasing alkali concentration. However, the power law dispersion of the ac conductivity scales regardless of the alkali concentration. This scaling property of the ac conductivity implies that inter-ionic interactions are not responsible for the non-Debye relaxation. In mixed alkali glasses, the exponent of the power law dispersion of the ac conductivity decreases and the dielectric relaxation strength increases relative to the single alkali glasses. With increasing total alkali concentration in the mixed alkali glasses, the frequency of maximum dielectric loss decreases, approaching frequencies comparable to that of the mixed alkali mechanical loss peak. These findings indicate a transition of the ionic relaxation toward a slower polarization process which is consistent with site memory mechanisms recently proposed for the mixed alkali effect.

Original languageEnglish
Pages (from-to)67-77
Number of pages11
JournalJournal of Non-Crystalline Solids
Volume255
Issue number1
DOIs
StatePublished - Sep 1999

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Alkalies
alkalies
Data storage equipment
Glass
glass
conductivity
Dielectric relaxation
Dielectric losses
germanium oxide
sodium oxide
Polarization
dielectric loss
exponents
scaling

All Science Journal Classification (ASJC) codes

  • Ceramics and Composites
  • Electronic, Optical and Magnetic Materials

Cite this

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title = "Evidence for site memory effects in the ionic relaxation of (Li2O)x(Na2O)y(GeO2)1-x-y glasses",
abstract = "We report measurements of the dielectric response due to ionic relaxation in alkali germanate glasses (Li2O)x(Na2O)y(GeO2)1-x-y. The relaxation is investigated in both electric modulus and ac conductivity formalisms, between which important discrepancies are observed. In single alkali glasses, the width of the electric modulus decreases with decreasing alkali concentration. However, the power law dispersion of the ac conductivity scales regardless of the alkali concentration. This scaling property of the ac conductivity implies that inter-ionic interactions are not responsible for the non-Debye relaxation. In mixed alkali glasses, the exponent of the power law dispersion of the ac conductivity decreases and the dielectric relaxation strength increases relative to the single alkali glasses. With increasing total alkali concentration in the mixed alkali glasses, the frequency of maximum dielectric loss decreases, approaching frequencies comparable to that of the mixed alkali mechanical loss peak. These findings indicate a transition of the ionic relaxation toward a slower polarization process which is consistent with site memory mechanisms recently proposed for the mixed alkali effect.",
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AU - Sidebottom, David L.

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N2 - We report measurements of the dielectric response due to ionic relaxation in alkali germanate glasses (Li2O)x(Na2O)y(GeO2)1-x-y. The relaxation is investigated in both electric modulus and ac conductivity formalisms, between which important discrepancies are observed. In single alkali glasses, the width of the electric modulus decreases with decreasing alkali concentration. However, the power law dispersion of the ac conductivity scales regardless of the alkali concentration. This scaling property of the ac conductivity implies that inter-ionic interactions are not responsible for the non-Debye relaxation. In mixed alkali glasses, the exponent of the power law dispersion of the ac conductivity decreases and the dielectric relaxation strength increases relative to the single alkali glasses. With increasing total alkali concentration in the mixed alkali glasses, the frequency of maximum dielectric loss decreases, approaching frequencies comparable to that of the mixed alkali mechanical loss peak. These findings indicate a transition of the ionic relaxation toward a slower polarization process which is consistent with site memory mechanisms recently proposed for the mixed alkali effect.

AB - We report measurements of the dielectric response due to ionic relaxation in alkali germanate glasses (Li2O)x(Na2O)y(GeO2)1-x-y. The relaxation is investigated in both electric modulus and ac conductivity formalisms, between which important discrepancies are observed. In single alkali glasses, the width of the electric modulus decreases with decreasing alkali concentration. However, the power law dispersion of the ac conductivity scales regardless of the alkali concentration. This scaling property of the ac conductivity implies that inter-ionic interactions are not responsible for the non-Debye relaxation. In mixed alkali glasses, the exponent of the power law dispersion of the ac conductivity decreases and the dielectric relaxation strength increases relative to the single alkali glasses. With increasing total alkali concentration in the mixed alkali glasses, the frequency of maximum dielectric loss decreases, approaching frequencies comparable to that of the mixed alkali mechanical loss peak. These findings indicate a transition of the ionic relaxation toward a slower polarization process which is consistent with site memory mechanisms recently proposed for the mixed alkali effect.

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