Scaling features of conductivity spectra reveal complexities in ionic, polaronic and mixed ionic-polaronic conduction in phosphate glasses

Šantić, Ana; Nikolić, Juraj; Pavić, Luka; Banhatti, Radha D.; Mošner, Petr; Koudelka, Ladislav; Moguš‐Milanković, Andrea

doi:10.1016/j.actamat.2019.05.067

Cited by 23 publications

(15 citation statements)

References 34 publications

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“…For all glasses in this study, Summerfield scaling procedure yields a perfect master-curve demonstrating that the time-temperature superposition (TTS) is valid and that the conductivity mechanism is temperature-invariant, as shown for B-2, B-8, B-14 and B-20 glasses in Figure 5. This is in line with the scaling properties of various oxide glasses that exhibit ionic [36,37] or polaronic conductivity [30,37]. Interestingly, our previous study on xB2O3-(40-x)-Fe2O3-60P2O5 (x = 0-20, mol.%) system showed that glass with 2 mol.% of B2O3 fails to produce a master-curve when Summerfield scaling procedure is applied [27].…”

Section: Frequency-dependent Conductivity and Scaling Propertiessupporting

confidence: 84%

Polaronic Conductivity in Iron Phosphate Glasses Containing B2O3

et al. 2020

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We report on the electrical properties of glasses with nominal composition xB2O3–(100 − x)[40Fe2O3–60P2O5],x = 2–20, mol.%. The conduction transport in these glasses is polaronic and shows a strong dependence on Fe2O3 content and polaron number density. The changes in DC conductivity are found not to be directly related to B2O3, however structural changes induced by its addition impact frequency-dependent conductivity. All glasses obey Summerfield and Sidebottom procedures of scaling conductivity spectra indicating that the polaronic mechanism does not change with temperature. An attempt to produce a super-master curve revealed that shape of the conductivity dispersion is the same for glasses with up to 15.0 mol.% B2O3 but differs for glass with the highest B2O3 content. This result could be related to the presence of borate units in the glass network. Moreover, the spatial extent of localized polaron motions increases with the decrease of polaron number density, however, this increase shows a larger slope than for previously reported iron phosphate glasses most probably due to the influence of B2O3 on glass structure and formation of polarons. While Summerfield scaling procedure fails, Sidebottom scaling yields a super-master curve, which indicates that polaronic hopping lengths also change with changing polaron number density in these glasses.

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Section: Frequency-dependent Conductivity and Scaling Propertiessupporting

confidence: 84%

Polaronic Conductivity in Iron Phosphate Glasses Containing B2O3

et al. 2020

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“…Indeed, for each glass in this study the application of Summerfield scaling yields a perfect conductivity master‐curve indicating that the time‐temperature superposition principle is valid and that the ionic conduction mechanism for all glasses does not change with temperature, see Figure 6. Moreover the validity of Summerfield scaling reveals that electrical transport in all glasses is due to one type of charge carrier and not a mixture of different types, that is, potassium ions and electrons (polarons) like it is found for mixed conductive phosphate‐based glasses 36 . This result again supports our conclusion that the conduction mechanism in these glasses is ionic without any significant contribution from electronic transport.…”

Section: Resultssupporting

confidence: 87%

Transport of potassium ions in niobium phosphate glasses

et al. 2021

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The influence of Nb2O5 on the structure and ionic conductivity of potassium phosphate glasses was investigated in glasses with composition xNb2O5–(100‐x)[0.45K2O–0.55P2O5], x = 10–47 mol%. The Raman spectra of glasses reveal a transition from predominantly orthophosphate to predominantly niobate glass network with increasing Nb2O5 content. In the glass structure, niobium forms NbO6 octahedra which are interlinked with phosphate units for the glass containing 10 mol% Nb2O5, but for higher Nb2O5 content they become mutually interconnected via Nb‐O‐Nb bonds. The transport of potassium ions was found to be strongly dependent on the structural characteristics of the glass network. While the mixed niobate‐phosphate glass network hinders the diffusion of potassium ions by providing traps that immobilize them and/or by blocking the conduction pathways, predominantly niobate glass network exhibits a rather facilitating effect which is evidenced in the trend of DC conductivity as well as in the features of the frequency‐dependent conductivity and typical hopping lengths of potassium ions.

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“…We shifted We could make important and indicative observations based on obtained slope values, see Figure 4c. The correlation between the validity of Summerfield scaling and the slope of one has been demonstrated in the literature [53,69]. In our case, for all compositions in this study, the slope is 1.01 ± 0.01, see Figure 4c, suggesting the validity of Summerfield scaling which will be shown and discussed in the following parts of the text.…”

Section: Scaling Features Of the Conductivity Spectrasupporting

confidence: 85%

“…A similar result is obtained for all other samples from this study and it shows that the time-temperature superposition (TTS) is valid for each composition and the conductivity mechanism does not change with temperature. A behavioral correlation could be undertaken with various oxide glasses that show polaronic [52,53,59,69] or ionic [66,69,70] conductivity, however, mixed ionic-polaronic glasses usually show deviation due to the presence of two different thermally active charge carrier species [69].…”

Section: Scaling Features Of the Conductivity Spectramentioning

confidence: 99%

“…At the same time, the DC conductivity trend shows a similar behavior and follows the changes of N v , see Figure 4. Looking at the changes in <r LOC 2 (∞)> 1/2 , one can see that, except for the sample F-B2Hf2 [69], the spatial extent of localized motions of polarons is in the low N v range (second region) with a value of ~3 Å. Once again, the polaron concentration is higher in S-series, except for S-B4Hf4, and all samples fall into the first region, which is characterized by a high N v value.…”

Section: Relevant Length Scales To Electrical Transportmentioning

confidence: 99%

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Electrical Transport in Iron Phosphate-Based Glass-(Ceramics): Insights into the Role of B2O3 and HfO2 from Model-Free Scaling Procedures

et al. 2022

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In this work, we report the effect of the addition of modifiers and network formers on the polaronic transport in iron phosphate glasses (IPG) in two systems of HfO2–B2O3–Fe2O3–P2O5, to which up to 8 mol% boron and hafnium are added. The addition of oxides significantly changes the Fe2+/Fetotal ratio, thus directly affecting the polaron number density and consequently controlling DC conductivity trends for both series studied by impedance spectroscopy. Moreover, we found that short-range polaron dynamics are also under the influence of structural changes. Therefore, we have studied them in detail using model-free scaling procedures, Summerfield and Sidebottom scaling. An attempt to construct a super-master curve revealed that in addition to change in polaron number density, also the polaron hopping lengths change, and Sidebottom scaling yields a super-master curve. The spatial extent of the localized motion of polarons is correlated with polaron number density and two distinct regions are observed. A strong increase in the spatial extent of the polaron hopping jump could be related either to the structural changes due to the addition of HfO2 and B2O3 and their effects on the formation of polarons or to an inherent property of polaron transport in IP glasses with low polaron number density.

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Scaling features of conductivity spectra reveal complexities in ionic, polaronic and mixed ionic-polaronic conduction in phosphate glasses

Cited by 23 publications

References 34 publications

Polaronic Conductivity in Iron Phosphate Glasses Containing B2O3

Polaronic Conductivity in Iron Phosphate Glasses Containing B2O3

Transport of potassium ions in niobium phosphate glasses

Electrical Transport in Iron Phosphate-Based Glass-(Ceramics): Insights into the Role of B2O3 and HfO2 from Model-Free Scaling Procedures

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