Defect and transport properties of nanocrystalline CeO2−<i>x</i>

Chiang, Yet‐Ming; Lavik, Erin B.; Kosacki, Igor; Tuller, Harry L.; Ying, Jackie Y.

doi:10.1063/1.117366

Cited by 383 publications

(268 citation statements)

References 6 publications

Supporting

Mentioning

244

Contrasting

Order By: Relevance

“…For catalytic applications CeO2 has to be grown on metallic substrates, but few studies exist on cerium oxide film deposited on metals and most of them have the aim to depict the epitaxial growth [6 and references therein]. CeO2 deposition is achieved by using a variety of growth techniques [7,8,9,10]. When highly stoichiometric oxide is required, atomic layer deposition (ALD) is the most suitable technique.…”

Section: Introductionmentioning

confidence: 99%

Atomic Layer Deposition of Cerium Dioxide Film on TiN and Si Substrates: Structural and Chemical Properties

Vangelista

Piagge

et al. 2017

MRS Advances

View full text Add to dashboard Cite

Cerium dioxide (CeO2) thin films were deposited by atomic layer deposition (ALD) on both Si and TiN substrates. The ALD growth produces CeO2 cubic polycrystalline films on both substrates. However, the films show a preferential orientation along <200> crystallographic direction for CeO2/Si or <111> for CeO2/TiN. In correspondence, we measure a relative concentration of Ce 3+ equals to 22.0% in CeO2/Si and around 18% in CeO2/TiN, by X-ray photoelectron spectroscopy. Such values indicate the presence of oxygen vacancies in the films. Our results extend the knowledge on the structural and chemical properties of ALD-deposited CeO2 either on Si or TiN substrates, underlying films differences and similarities, thus contributing to boost the use of CeO2 through ALD deposition as foreseen in a wide number of applications.

show abstract

Section: Introductionmentioning

confidence: 99%

Atomic Layer Deposition of Cerium Dioxide Film on TiN and Si Substrates: Structural and Chemical Properties

Vangelista

Piagge

et al. 2017

MRS Advances

View full text Add to dashboard Cite

show abstract

“…Even in the absence of re-adsorption, a desorption peak temperature of 623 K would correspond to an activation energy for desorption of roughly 200 kJ/mol of O 2 , compared to the tabulated value for the oxidation enthalpy for Ce 2 O 3 of -760 kJ/mol-O 2 [25]. Third, electrical conductivity measurements have indicated that the enthalpy of reduction for ceria nano-particles is half that of bulk ceria [26,27]. Finally, Rodriguez and coworkers used X-ray Near Edge Spectroscopy and other techniques to suggest that ceria and ceria-zirconia nano-particles reduce more easily [28].…”

Section: Introductionmentioning

confidence: 99%

Oxidation enthalpies for reduction of ceria surfaces

et al. 2007

View full text Add to dashboard Cite

The thermodynamic properties of surface ceria were investigated through equilibrium isotherms determined by flow-titration and coulometric-titration measurements on high-surface-area ceria and ceria supported on La-modified alumina (LA). While the surface area of pure ceria was found to be unstable under redox conditions, the extent of reduction at 873 K and a P(O 2 ) of 1.6x10 -26 atm increased with surface area. Because ceria/LA samples were stable, equilibrium isotherms were determined between 873 and 973 K on a 30-wt% ceria sample. Oxidation enthalpies on ceria/LA were found to vary with the extent of reduction, ranging from -500 kJ/mol O 2 at low extents of reduction to near the bulk value of -760 kJ/mol O 2 at higher extents. To determine whether +3 dopants could affect the oxidation enthalpies for ceria, isotherms were measured for Sm +3 -doped ceria (SDC) and Y +3 -doped ceria. These dopants were found to remove the phase transition observed in pure ceria below 973 K but appeared to have minimal effect on the oxidation enthalpies. Implications of these results for catalytic applications of ceria are discussed. AbstractThe thermodynamic properties of surface ceria were investigated through equilibrium isotherms determined by flow-titration and coulometric-titration measurements on high-surfacearea ceria and ceria supported on La-modified alumina (LA). While the surface area of pure ceria was found to be unstable under redox conditions, the extent of reduction at 873 K and a P(O 2 ) of 1.6x10 -26 atm increased with surface area. Because ceria/LA samples were stable, equilibrium isotherms were determined between 873 and 973 K on a 30-wt% ceria sample. Oxidation enthalpies on ceria/LA were found to vary with the extent of reduction, ranging from -500 kJ/mol O 2 at low extents of reduction to near the bulk value of -760 kJ/mol O 2 at higher extents.To determine whether +3 dopants could affect the oxidation enthalpies for ceria, isotherms were measured for Sm +3 -doped ceria (SDC) and Y +3 -doped ceria. These dopants were found to remove the phase transition observed in pure ceria below 973 K but appeared to have minimal effect on the oxidation enthalpies. Implications of these results for catalytic applications of ceria are discussed.

show abstract

“…They observed that samples sintered at 1400°C showed higher oxygen conductivity than those sintered at 1500°C, and argued that larger density of grain boundaries in 1400°C samples provided more area for the dopants to segregate for a given concentration of dopants. Eventually dopant segregation could cause depletion in the oxygen vacancy concentration in the vicinity of the grain boundaries as per the space-charge layer model, 101,102 thus reducing the overall conductivity. Thus, in view of these experimental observations, it appears that instead of the blocking effect of grain boundaries, larger focus may be required on preventing dopant segregation.…”

Section: Effect Of Dopant Segregation On Oxygen Energeticsmentioning

confidence: 99%

“…They performed diffusivity measurements using MD simulations on four dislocations, i.e., [100]{110}, [110]{110}, [101]{110} and a screw dislocation. Surprisingly, in all four dislocations, they observed enhancement in oxygen diffusivity, and the activation energies were significantly lower than those in the bulk.…”

Section: Misfit Dislocationsmentioning

confidence: 99%

Microstructure design for fast oxygen conduction

Aidhy

Weber

2015

J. Mater. Res.

View full text Add to dashboard Cite

In the past decade, the research in designing fast oxygen conducting materials for electrochemical applications has largely shifted to microstructural features, in contrast to material-bulk. In particular, understanding oxygen energetics in heterointerface materials is currently at the forefront, where interfacial tensile strain is being considered as the key parameter in lowering oxygen migration barriers. Nanocrystalline materials with high densities of grain boundaries have also gathered interest that could possibly allow leverage over excess volume at grain boundaries, providing fast oxygen diffusion channels similar to those previously observed in metals. In addition, near-interface phase transformations and misfit dislocations are other microstructural phenomenon/features that are being explored to provide faster diffusion. In this review, the current understanding on oxygen energetics, i.e., thermodynamics and kinetics, originating from these microstructural features is discussed. Experimental observations, theoretical predictions and novel atomistic mechanisms relevant to oxygen transport are highlighted. In addition, the interaction of dopants with oxygen vacancies in the presence of these new microstructural features, and their future role in the design of future fast-ion conductors, is outlined.

show abstract

Defect and transport properties of nanocrystalline CeO2−x

Cited by 383 publications

References 6 publications

Atomic Layer Deposition of Cerium Dioxide Film on TiN and Si Substrates: Structural and Chemical Properties

Atomic Layer Deposition of Cerium Dioxide Film on TiN and Si Substrates: Structural and Chemical Properties

Oxidation enthalpies for reduction of ceria surfaces

Microstructure design for fast oxygen conduction

Contact Info

Product

Resources

About