LCAO Calculations of (001) Surface Oxygen Vacancy Structure in Y-Doped BaZrO<sub>3</sub>

Bandura, Andrei V.; Ėvarestov, R. A.; Kuruch, Dmitry D.

doi:10.1080/10584587.2011.570582

Cited by 5 publications

(8 citation statements)

References 20 publications

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“…At low temperature, (single-, di-) vacancies cannot overcome the migration energy barrier and they form static clusters within the filament bundles. The values of these barriers at the surface, namely 0.14 -0.2 eV and 0.4 eV for single-and di-vacancy motion respectively [24,32,33], closely match the trapping energies that were determined by Seri et al [19] for LAO/STO and were shown to correspond to two recovery temperatures at 70 K and 160 K as is also observed in the present study. Since vacancy motions are correlated within a bundle, one expects only small variations in the value of the trapping current for sample widths less than 10 µm.…”

Section: Discussionsupporting

confidence: 90%

Current-induced nonuniform enhancement of sheet resistance in Ar+ -irradiated SrTiO3

et al. 2017

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The sheet resistance Rs of Ar + irradiated SrTiO3 in patterns with a length scale of several microns increases significantly below ~40 K in connection with driving currents exceeding a certain threshold. The initial lower Rs is recovered upon warming with accelerated recovery around 70 and 160 K. Scanning SQUID microscopy shows local irreversible changes in the spatial distribution of the current with a length scale of several microns. We attribute the observed non-uniform enhancement of Rs to the attraction of the charged single-and di-oxygen vacancies by the crystallographic domain boundaries in SrTiO3. The boundaries which are nearly ferroelectric below 40 K are polarized by the local electrical field associated with the driven current and the clustered vacancies which suppress conductivity in their vicinity yield a noticeable enhancement in the device resistance when the current path width is on the order of the boundary extension. The temperatures of accelerated conductivity recovery are associated with the energy barriers for the diffusion of the two types of vacancies.2

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Section: Discussionsupporting

confidence: 90%

Current-induced nonuniform enhancement of sheet resistance in Ar+ -irradiated SrTiO3

et al. 2017

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“…The incorporation of Y atoms in ZrO 2 -terminated surface is accomplished by a noticeable reconstruction of the surface structure around the oxygen vacancy [19]. We found that the energy of formation of the isolated surface oxygen vacancy from the bare (001) BaZrO 3 surface and ZrO 2 and Y 2 O 3 stable bulk phases is about 130-150 kJ/mol and it depends on concrete positions of Y substituents at the vacancy vicinity.…”

Section: Water Adsorption Sites and Corresponding Energiesmentioning

confidence: 95%

“…To establish the 2Y model we apply the obtained in Ref. [19] stable structure (Sur″Y 4 □ 2 ). For calculations of the water adsorption energy the corresponding total energy is substituted in Eqs.…”

Section: Water Adsorption Sites and Corresponding Energiesmentioning

confidence: 99%

“…Prior to study of the water adsorption on the defective BaZrO 3 surface we considered [19] the different positions of Y atom in the top and nextto-top atomic planes to establish the most favorable surface vacancydopant configurations using the 2×2 or 3×3 surface unit cells. The incorporation of Y atoms in ZrO 2 -terminated surface is accomplished by a noticeable reconstruction of the surface structure around the oxygen vacancy [19].…”

Section: Water Adsorption Sites and Corresponding Energiesmentioning

confidence: 99%

“…However, the calculations of the defective bare and protonated surface structures were not made at all. In our previous works we studied the water adsorption on the bare (001) BaZrO 3 surface [18] and the oxygen vacancy structure at (001) surface of Y-doped BaZrO 3 [19] using the first-principles periodic calculations. In this work we extend these calculations to the water molecule adsorption and dissociation on the defective surface of cubic BaZrO 3 .…”

Section: Introductionmentioning

confidence: 99%

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LCAO calculation of water adsorption on (001) surface of Y-doped BaZrO3

Ėvarestov

Bandura

2011

Solid State Ionics

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Surface Segregation Entropy of Protons and Oxygen Vacancies in BaZrO₃

et al. 2016

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The perovskite BaZrO3 has attracted considerable attention in the recent decade due to its high temperature proton conducting properties, and possible application as electrolyte in intermediate temperature fuel cells and electrolyzers. In this contribution, we performed, for the first time, first-principles calculations of the phonon contribution to the defect thermodynamics of the ZrO2 terminated (001) surface of BaZrO3. The approach allows us to determine both the segregation enthalpy and entropy of defects, which we apply to two fundamental defects in BaZrO3; fully charged oxygen vacancies (vO ••) and protonic defects (OHO •). The calculations show that both defects exhibit favorable segregation enthalpies of −65 and −125 kJ/mol, respectively. Further, the vibrational formation entropy of the surface vO •• is significantly higher than that of the bulk vO ••, due to smaller local structural relaxations of the surface defect, leading to a finite surface segregation entropy of 53 J/mol K. OHO •, on the other hand, displays nearly identical vibrational spectra at the surface and in the bulk, and the segregation entropy is therefore negligible. Hence, phonons not only stabilize the surface vO •• compared to the bulk defect thermodynamically at high temperatures, but also affect the relative stability of vO •• and OHO • at the surface. Finally, we apply a simplified space charge model to the (001) surface, and show that neglect of phonons results in strongly underestimated surface concentrations of vO ••.

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LCAO Calculations of (001) Surface Oxygen Vacancy Structure in Y-Doped BaZrO₃

Cited by 5 publications

References 20 publications

Current-induced nonuniform enhancement of sheet resistance in Ar+ -irradiated SrTiO3

Current-induced nonuniform enhancement of sheet resistance in Ar+ -irradiated SrTiO3

LCAO calculation of water adsorption on (001) surface of Y-doped BaZrO3

Surface Segregation Entropy of Protons and Oxygen Vacancies in BaZrO₃

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LCAO Calculations of (001) Surface Oxygen Vacancy Structure in Y-Doped BaZrO3

Cited by 5 publications

References 20 publications

Current-induced nonuniform enhancement of sheet resistance in Ar+ -irradiated SrTiO3

Current-induced nonuniform enhancement of sheet resistance in Ar+ -irradiated SrTiO3

LCAO calculation of water adsorption on (001) surface of Y-doped BaZrO3

Surface Segregation Entropy of Protons and Oxygen Vacancies in BaZrO3

Contact Info

Product

Resources

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LCAO Calculations of (001) Surface Oxygen Vacancy Structure in Y-Doped BaZrO₃

Surface Segregation Entropy of Protons and Oxygen Vacancies in BaZrO₃