Small polaron electron transport in reduced CeO2 single crystals

Tuller, Harry L.; Nowick, A. S.

doi:10.1016/0022-3697(77)90124-x

Cited by 609 publications

(420 citation statements)

References 22 publications

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“…Experimental study based on 17 We also neglect the effect of having polarons near the vacancy as previously studied [36]. At high temperatures typically used to measure ionic conductivity, polarons are likely to be unbound to the vacancies as discussed below.…”

Section: E Oxygen Vacancy Migrationmentioning

confidence: 99%

“…When an oxygen vacancy is formed in CeO 2 , two electrons are left behind; instead of behaving as delocalized electrons in the conduction band or occupying a defect-related state, these excess electrons prefer to localize on Ce atoms neighboring the vacancy, as small polarons (Ce 3+ ) [10,15,16]. These small polarons can escape from the oxygen vacancy and contribute to the electronic conductivity of CeO 2 [17]. Therefore, to further the development of CeO 2 in energy-related applications that depend on catalytic or OSC properties, it is essential to develop a deeper understanding and quantitative description of the behavior of the oxygen vacancy, the small polaron, and their interactions.…”

Section: Introductionmentioning

confidence: 99%

“…The electronic conductivity in CeO 2 is thermally activated and occurs via hoping of small polarons [17] rather than through delocalized electrons in the conduction band. On the other hand, the ionic conductivity, that typically dominates the charge transport at high temperatures, has been attributed to the migration of ionized oxygen vacancies [24].…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, the ionic conductivity, that typically dominates the charge transport at high temperatures, has been attributed to the migration of ionized oxygen vacancies [24]. Reported experimental values for the activation energy for electronic conductivity vary in a wide range [17,25]. Tuller and Nowick [17] reported an activation energy of 0.40 eV, while Blumenthal et al [25] reported lower values of 0.16 eV and 0.22 eV.…”

Section: Introductionmentioning

confidence: 99%

“…Reported experimental values for the activation energy for electronic conductivity vary in a wide range [17,25]. Tuller and Nowick [17] reported an activation energy of 0.40 eV, while Blumenthal et al [25] reported lower values of 0.16 eV and 0.22 eV. For the migration of oxygen vacancies, experimental values for the motion energy vary from 0.49 eV to 0.61 eV [26,27].…”

Section: Introductionmentioning

confidence: 99%

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Disentangling the role of small polarons and oxygen vacancies in CeO2

et al. 2017

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The outstanding performance of cerium oxide (CeO 2 ) as ion conductor or catalyst strongly depends on the ease of Ce 4+ ↔Ce 3+ conversion and oxygen vacancyformation. An accurate description of Ce 3+ and oxygen vacancy is therefore essential to further progress in this area. Using the HSE06 hybrid functional, we investigate the formation and migration of small polarons (Ce 3+ ) and their interaction with oxygen vacancies in CeO 2 , considering the small polaron and vacancy as independent entities.Oxygen vacancies are double donors and can bind up to two small polarons, forming a positively charged or neutral complex. We compute the electron self-trapping energy (i.e., energy gain when forming a small polaron), the small-polaron migration barrier, vacancy formation and migration energies, and vacancy-polaron binding energies. We find that small polarons weakly bind to oxygen vacancies, yet this interaction significantly contributes to the activation energy for hopping electronic conductivity.The results are compared with previous calculations and discussed in the light of available experimental data.

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Section: E Oxygen Vacancy Migrationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Disentangling the role of small polarons and oxygen vacancies in CeO2

et al. 2017

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Electrolyte‐Free SOFCs

Fan

Kim

Lund

2020

Solid Oxide Fuel Cells

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Understanding Chemical Expansion in Non‐Stoichiometric Oxides: Ceria and Zirconia Case Studies

Marrocchelli¹,

Bishop²,

Tuller³

et al. 2012

Adv Funct Materials

347

335

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Atomic scale computer simulations, validated with experimental data, are used to uncover the factors responsible for defect‐induced chemical expansion observed in non‐stoichiometric oxides, exemplified by CeO2 and ZrO2. It is found that chemical expansion is the result of two competing processes: the formation of a vacancy (leading to a lattice contraction primarily due to electrostatic interactions) and the cation radius change (leading to a lattice expansion primarily due to steric effects). The chemical expansion coefficient is modeled as the summation of two terms that are proportional to the cation and oxygen radius change. This model introduces an empirical parameter, the vacancy radius, which can be reliably predicted from computer simulations, as well as from experimental data. This model is used to predict material compositions that minimize chemical expansion in fluorite structured solid oxide fuel cell electrolyte materials under typical operating conditions.

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Small polaron electron transport in reduced CeO2 single crystals

Cited by 609 publications

References 22 publications

Disentangling the role of small polarons and oxygen vacancies in CeO2

Disentangling the role of small polarons and oxygen vacancies in CeO2

Electrolyte‐Free SOFCs

Understanding Chemical Expansion in Non‐Stoichiometric Oxides: Ceria and Zirconia Case Studies

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