Dielectric dispersion and ac conduction phenomena of Li2O−Sb2O3−PbO−GeO2:Cr2O3 glass system

Vijay, R.; Babu, P. Ramesh; Kumar, V. Ravi; Piasecki, M.; Rao, D. Krishna; Veeraiah, N.

doi:10.1016/j.mssp.2015.02.082

Cited by 40 publications

(13 citation statements)

References 64 publications

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“…Similar dispersion behavior has been exhibited by other glasses of the present series. This result is in agreement with observations made in [24]. The frequency corresponding to maximum M′′ is known as relaxation frequency fM.…”

Section: Conductivity Master Curvessupporting

confidence: 92%

DIELECTRIC STUDIES IN Li2O AND CoO DOPED BOROPHOSPHATE GLASSES

Talari

Ashwajeet

Ramanna

et al. 2015

JAP

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Borophosphate glasses in the compositions, (B2O3)0.2 . (P2O5)0.3 . (Li2O) 0.5-X . (CoO) X, wherex = 0.05, 0.1, 0.15, 0.25, 0.30, 0.35, 0.40 and 0.45 were prepared at 1400K by following melt quenching method. Their amorphous nature was confirmed by XRD studies and was investigated for dielectric properties in the frequency range from 100Hz to 1MHz and temperature range from 300K to 573K. The conductivity was derived from the dielectric spectrum. The frequency exponent, s, dc and ac components of the conductivity were determined. The temperature dependence of conductivity at different frequencies was analyzed using Mottâ€™s small polaron hopping model, and the high temperature activation energy has been estimated and discussed. The variation of conductivity and activation energy with composition revealed a changeover of conduction mechanism from predominantly ionic to electronic regime for mole fractions of CoO between 0.3 and 0.35. This is a new result. Huntâ€™s model has been employed to analyze frequency dependence of conductivity. Relaxation features of the dielectric properties have been extracted from the analysis of electric moduli with frequency. Activation energy for relaxation mechanism has been determined. Frequency exponent was found to be temperature dependent. Quantum mechanical theory and correlated barrier hopping models were found to be inadequate to explain frequency exponent behavior with temperature.For the first time that borophosphate glasses doped with Li2O and CoO were studied for dielectric properties and ac conductivity as a function of temperature and frequency and the data has been analysed thoroughly.Â

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Section: Conductivity Master Curvessupporting

confidence: 92%

DIELECTRIC STUDIES IN Li2O AND CoO DOPED BOROPHOSPHATE GLASSES

Talari

Ashwajeet

Ramanna

et al. 2015

JAP

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“…However, for the sake of clarification, we have presented the IR spectrum for one of the samples, viz, Au 100 in Figure B. The spectrum exhibited vibrational bands due to ν 1 , ν 2, ν 3, ν 4 ‐vibrations of Sb–O bonds in SbO 3 structural units at about 975, 600, 750, and 445 cm −1 , respectively . With a gradual increase in Au 2 O 3 content, the intensity of symmetrical stretching vibrational band (v 1 ) is observed to increase while that of bending vibrational band (v 2 ) exhibited a decreasing trend (inset of Figure B).…”

Section: Resultsmentioning

confidence: 99%

Structural and physical characteristics of Au₂O₃‐doped sodium antimonate glasses – Part II electrical characteristics

et al. 2018

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In continuation of our earlier investigations on structural and physical characteristics of Au2O3‐doped sodium antimonate glass‐ceramics (Part‐1), in this part we have investigated the influence of gold ions on electrical characteristics of the Na2O–Sb2O3: Au2O3 glass‐ceramics. The study contains the results of quantitate investigations on dielectric properties, impedance spectra and A.C. conductivity in larger ranges of continuous frequencies (4 Hz‐8 MHz) and temperatures (300‐630 K). The variations exhibited by dielectric parameters with temperature and also with frequency were discussed in terms of various polarization mechanisms. The observed dielectric relaxation effects were analyzed using pseudo Cole‐Cole plot method and the analysis indicated spreading of relaxation times for dipoles. A.c. conductivity and also d.c. conductivity were found to decrease (to three orders of magnitude) with increase in Au2O3 concentration upto 0.1 mol%. The decrement is ascribed to the increasing concentration of Sb5+ ions that were predicted to participate in the glass network forming with SbO4 units. Even though, both ionic and polaronic contributions are possible for conduction in the studied material, quantitative analysis of these results indicated that the polaronic conduction (due to intervalence transfer between Sb3+ ↔ Sb5+ and Au0 ↔ Au3+) is prevalent. The results have also suggested that there is a gradual decrement in the ionic component with increase in Au2O3 concentration. Variation in σac in the low‐temperature region could satisfactorily be explained using quantum mechanical tunneling (QMT) model. Analysis of the results of d.c. conductivity indicated that the small polaron hoping (SPH) model is valid, especially in a high‐temperature region while the low temperature part of d.c. conductivity is analyzed based on variable range hopping (VRH) model. Overall, the increase in Au2O3 dopant concentration in the studied glass‐ceramics caused a decrement in the magnitude of the conductivity or increase in the insulating strength of the material.

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“…The authors have suggested that a partial change of the GeO 4 tetrahedra to GeO 6 octahedra occurs with the increase of the alkali content, altering the germanium coordination number from four to six. Recently, Vijay et al [24] also verified that the transition metal chromium, like the alkali metals, has a similar effect in the germanate glasses. The octahedral chromium ions act as modifiers and cause disruptions of GeÀ ÀOÀ ÀGe, contributing to the increase of GeO 6 structural groups.…”

Section: Raman Spectra Of the Glass Samplesmentioning

confidence: 90%

Thermal and structural analysis of germanate glass and thin films co-doped with silver nanoparticles and rare earth ions with insights from visible and Raman spectroscopy

Carvalho

Freitas

Silva

et al. 2016

Vibrational Spectroscopy

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This paper reports on the thermal and optical properties of germanate glasses GeO 2-PbO co-doped with silver nanoparticles and rare earth ions (Tm 3+ , Er 3+ and Yb 3+) with a focus on the thermal diffusivity (D). The presence of rare earth ions and nanoparticles is evidenced by absorption spectra and TEM images, respectively. Additionally, a structural comparison between thin films and bulk glass with the same nominal composition is given. It is found that D increases up to 20% in samples where nanoparticles are present, although their quantity corresponds only to a volume fraction of 1.7%. Therefore, such enhancement could be associated with the nanoparticles. Nevertheless, a Raman analysis revealed a structural change after the thermal treatment used for the nucleation of the nanoparticles. A decrease in the intensity of the band at 534 cm À1 in the Raman spectra is interpreted as the disruption of the 3-membered rings of the GeO 4 tetrahedra. The Raman analysis also revealed the formation of small crystals of a-GeO 2 type quartz and the adsorption of carbon dioxide on the surface of the silver nanoparticles inserted in the germanate thin film. 2016 Elsevier B.V. All rights reserved.

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Dielectric dispersion and ac conduction phenomena of Li2O−Sb2O3−PbO−GeO2:Cr2O3 glass system

Cited by 40 publications

References 64 publications

DIELECTRIC STUDIES IN Li2O AND CoO DOPED BOROPHOSPHATE GLASSES

DIELECTRIC STUDIES IN Li2O AND CoO DOPED BOROPHOSPHATE GLASSES

Structural and physical characteristics of Au₂O₃‐doped sodium antimonate glasses – Part II electrical characteristics

Thermal and structural analysis of germanate glass and thin films co-doped with silver nanoparticles and rare earth ions with insights from visible and Raman spectroscopy

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Dielectric dispersion and ac conduction phenomena of Li2O−Sb2O3−PbO−GeO2:Cr2O3 glass system

Cited by 40 publications

References 64 publications

DIELECTRIC STUDIES IN Li2O AND CoO DOPED BOROPHOSPHATE GLASSES

DIELECTRIC STUDIES IN Li2O AND CoO DOPED BOROPHOSPHATE GLASSES

Structural and physical characteristics of Au2O3‐doped sodium antimonate glasses – Part II electrical characteristics

Thermal and structural analysis of germanate glass and thin films co-doped with silver nanoparticles and rare earth ions with insights from visible and Raman spectroscopy

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Structural and physical characteristics of Au₂O₃‐doped sodium antimonate glasses – Part II electrical characteristics