High temperature scanning tunneling microscopy of purely ion conducting yttria stabilized zirconia (YSZ)

Morrow, Suzanne L.; Luttrell, Tim; Carter, Aaron; Batzill, Matthias

doi:10.1016/j.susc.2009.04.009

Cited by 12 publications

(14 citation statements)

References 16 publications

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“…The results obtained from (anomalous) surface X-ray diffraction are consistent with DFT calculations [8], STM measurements [22] and bulk X-ray diffraction [20]. Our results reveal an increased Y concentration at the surface and a high vacancy density, of both Zr and oxygen, in the topmost layer under both studied conditions.…”

Section: Discussionsupporting

confidence: 87%

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Atomic structure and composition of the yttria-stabilized zirconia (111) surface

et al. 2013

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Anomalous and nonanomalous surface X-ray diffraction is used to investigate the atomic structure and composition of the yttria-stabilized zirconia (YSZ)(111) surface. By simulation it is shown that the method is sensitive to Y surface segregation, but that the data must contain high enough Fourier components in order to distinguish between different models describing Y/Zr disorder. Data were collected at room temperature after two different annealing procedures. First by applying oxidative conditions at 10− 5 mbar O2 and 700 K to the as-received samples, where we find that about 30% of the surface is covered by oxide islands, which are depleted in Y as compared with the bulk. After annealing in ultrahigh vacuum at 1270 K the island morphology of the surface remains unchanged but the islands and the first near surface layer get significantly enriched in Y. Furthermore, the observation of Zr and oxygen vacancies implies the formation of a porous surface region. Our findings have important implications for the use of YSZ as solid oxide fuel cell electrode material where yttrium atoms and zirconium vacancies can act as reactive centers, as well as for the use of YSZ as substrate material for thin film and nanoparticle growth where defects control the nucleation process.

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Section: Discussionsupporting

confidence: 87%

“…Also Scanning Tunneling Microscopy (STM) reveals a surface morphology containing islands [22], even after annealing to 1270 K at 1 bar oxygen pressure. The STM measurements indicate the presence of islands about 0.2 nm high, 1 nm wide and with a lateral spacing of 1–2 nm, which results in a surface coverage in the 25–50% range.…”

Section: Discussionmentioning

confidence: 99%

Atomic structure and composition of the yttria-stabilized zirconia (111) surface

et al. 2013

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“…Morterra et al found that Y stabilized t‐ZrO 2 appears to show small coin‐like morphology with the (111) surface favored at a lower calcination temperature of approximately 600°C, and this morphology changes to pebble‐like crystals with (101) as a dominant surface at a higher calcination temperature. Some recent studies proposed that the surface morphological changes might be more stable than some flat YSZ surface …”

Section: Resultsmentioning

confidence: 99%

A comprehensive sintering mechanism for TBCs‐Part II: Multiscale multipoint interconnection‐enhanced initial kinetics

et al. 2017

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During thermal exposure, the sintering process of the plasma‐sprayed thermal barrier coatings (PS‐TBCs) presents significant two‐stage kinetics, as reported in the Part I. As a companion study, this part aims to reveal the mechanism responsible for the ultrafast sintering kinetics when initially exposed, since the initial short stage (stage‐I) often finishes most increment of the mechanical and thermal properties. A detailed examination of the pore healing behavior was carried out, based on the experimental result in Part I that the dominant structural change at the stage‐I is the significant healing at intersplat pore tips. Results show that the smooth splat surface, which made up the wedge‐shaped intersplat pores, changed to a rough surface with multiscale convexs after high‐temperature thermal exposure. Moreover, the multiscale roughening is highly sensitive to various orientations of the columnar grains inside the splats. Subsequently, multipoint connection between the counter‐surfaces of the intersplat pores was formed by the bridging of multiscale convexs. This multiscale multipoint connection between pore surfaces significantly accelerated the healing of intersplat pores, which can be dominantly responsible for the ultrafast sintering kinetics at the stage‐I. This comprehensive sintering mechanism could offer some positive suggestions toward prolonging the thermal‐insulating effect of TBCs.

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“…23 In any case all our fit results do indicate a surface morphology composed of nanoscaled islands of uniform well-defined 0.25 nm height, almost identical to what was found for the YSZ(111) surface. 9,24 …”

Section: Resultsmentioning

confidence: 99%

Operando X-ray Investigation of Electrode/Electrolyte Interfaces in Model Solid Oxide Fuel Cells

et al. 2016

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We employed operando anomalous surface X-ray diffraction to investigate the buried interface between the cathode and the electrolyte of a model solid oxide fuel cell with atomic resolution. The cell was studied under different oxygen pressures at elevated temperatures and polarizations by external potential control. Making use of anomalous X-ray diffraction effects at the Y and Zr K-edges allowed us to resolve the interfacial structure and chemical composition of a (100)-oriented, 9.5 mol % yttria-stabilized zirconia (YSZ) single crystal electrolyte below a La0.6Sr0.4CoO3−δ (LSC) electrode. We observe yttrium segregation toward the YSZ/LSC electrolyte/electrode interface under reducing conditions. Under oxidizing conditions, the interface becomes Y depleted. The yttrium segregation is corroborated by an enhanced outward relaxation of the YSZ interfacial metal ion layer. At the same time, an increase in point defect concentration in the electrolyte at the interface was observed, as evidenced by reduced YSZ crystallographic site occupancies for the cations as well as the oxygen ions. Such changes in composition are expected to strongly influence the oxygen ion transport through this interface which plays an important role for the performance of solid oxide fuel cells. The structure of the interface is compared to the bare YSZ(100) surface structure near the microelectrode under identical conditions and to the structure of the YSZ(100) surface prepared under ultrahigh vacuum conditions.

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High temperature scanning tunneling microscopy of purely ion conducting yttria stabilized zirconia (YSZ)

Cited by 12 publications

References 16 publications

Atomic structure and composition of the yttria-stabilized zirconia (111) surface

Atomic structure and composition of the yttria-stabilized zirconia (111) surface

A comprehensive sintering mechanism for TBCs‐Part II: Multiscale multipoint interconnection‐enhanced initial kinetics

Operando X-ray Investigation of Electrode/Electrolyte Interfaces in Model Solid Oxide Fuel Cells

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