Effect of rare-earth oxides on fracture properties of ceria ceramics

Sato, Kazuhisa; Yugami, Hiroo; Hashida, Toshiyuki

doi:10.1023/b:jmsc.0000040087.37727.cd

Cited by 77 publications

(58 citation statements)

References 5 publications

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“…As it can be seen in Table 4, E 0 of all samples were calculated to avoid the effect of porosity. Elastic modulus of pure ceria is higher than doped ceria samples, which confirmed the previous reports on Y-, Sm-and Gd-doped ceria [29].…”

Section: Resultssupporting

confidence: 91%

“…7. All doped ceria samples showed higher hardness than pure ceria, which is in agreement with the reported results in literature [29]. EDC sample demonstrated the highest hardness that could be related to improving the atomic bonds by doping ceria with Er as it was seen in elastic modulus measurement earlier and YDC samples has the lowest hardness among doped ceria samples, which could attributed to lower density due to having high porosity [15,19].…”

Section: +supporting

confidence: 90%

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Effect of rare earth dopants on structural and mechanical properties of nanoceria synthesized by combustion method

Akbari‐Fakhrabadi

Meruane

Jamshidijam

et al. 2016

Materials Science and Engineering: A

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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. E-mail: aliakbarif@ing.uchile.cl Abstract Structural characteristics of combustion synthesized, calcined and densified pure and doped nanoceria with tri-valent cations of Er, Y, Gd, Sm and Nd were analyzed by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). The results showed that the as-synthesized and calcined nanopowders were mesoporous and calculated lattice parameters were close to theoretical ion-packing model. The effect of dopants on elastic modulus, microhardness and fracture toughness of sintered pure and doped ceria were investigated. It was observed that tri-valent cation dopants increased the hardness of the ceria, whereas the fracture toughness and elastic modulus were decreased.

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Section: Resultssupporting

confidence: 91%

Section: +supporting

confidence: 90%

Effect of rare earth dopants on structural and mechanical properties of nanoceria synthesized by combustion method

Akbari‐Fakhrabadi

Meruane

Jamshidijam

et al. 2016

Materials Science and Engineering: A

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“…This difference is related to be the effects of porosity and possibly experimental errors. However, the bulk elastic modulus results measured by bending tests of this work are comparable to the literature reported bending modulus values for both ceria and GDC 34 .…”

Section: Elastic Modulus: Polycrystallinesupporting

confidence: 87%

Determination of Electrochemical Performance and Thermo-Mechanical-Chemical Stability of SOFCs from Defect Modeling

Wachsman¹,

Duncan²

2006

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This research was focused on two distinct but related issues. The first issue concerned using defect modeling to understand the relationship between point defect concentration and the electrochemical, thermo-chemical and mechano-chemical properties of typical solid oxide fuel cell (SOFC) materials.The second concerned developing relationships between the microstructural features of SOFC materials and their electrochemical performance.To understand the role point defects play in ceramics, a coherent analytical framework was used to develop expressions for the dependence of thermal expansion and elastic modulus on point defect concentration in ceramics. These models, collectively termed the continuum-level electrochemical model (CLEM), were validated through fits to experimental data from electrical conductivity, I-V characteristics, elastic modulus and thermo-chemical expansion experimentsfor (nominally pure) ceria, gadolinia-doped ceria (GDC) and yttria-stabilized zirconia (YSZ) with consistently good fits. The same values for the material constants were used in all of the fits, further validating our approach. As predicted by the continuum-level electrochemical model, the results reveal that the concentration of defects has a significant effect on the physical properties of ceramic materials and related devices.Specifically, for pure ceria and GDC, the elastic modulus decreased while the chemical expansion increased considerably in low partial pressures of oxygen. Conversely, the physical properties of YSZ remained insensitive to changes in oxygen partial pressure within the studied range. Again, the findings concurred exactly with the predictions of our analytical model.Indeed, further analysis of the results suggests that an increase in the point defect content weakens the attractive forces between atoms in fluorite-structured oxides.The reduction treatment effects on the flexural strength and the fracture toughness of pure ceria were also evaluated at room temperature. The results reveal that the flexural strength decreases significantly after heat treatment in very low oxygen partial pressure environments;however, in contrast, fracture toughness is increased by 30-40% when the oxygen partial pressure was decreased to 10 -20 to 10 -22 atm range. Fractographic studies show that microcracks developed at 800 o C upon hydrogen reduction are responsible for the decreased strength.iv To understand the role of microstructure on electrochemical performance, electrical impedance spectra from symmetric LSM/YSZ/LSM cells was de-convoluted to obtain the key electrochemical components of electrode performance, namely charge transfer resistance, surface diffusion of reactive species and bulk gas diffusion through the electrode pores. These properties were then related to microstructural features, such as triple-phase boundary length and tortuosity.From these experiments we found that the impedance due to oxygen adsorption obeys a power law with pore surface area, while the impedance due to charge transfer is found...

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“…The Young's modulus obtained from these calculations is 221.8 GPa on the [001] axis and the experimental Young's modulus is 175 GPa. 42 These values are similar. In this model, a crystalline material with no faults, such as grain boundaries or cracks, is used.…”

Section: Resultsmentioning

confidence: 61%

“…A fracture strength of 22.7 GPa is obtained from the DFT calculation, whereas the experimental value is 0.250 GPa. 42 The mechanical properties generally depend on factors such as the grain size, defects, flaws, cracks, voids, and grain boundaries. These factors are affected by experimental preparation techniques, thus it is difficult to directly compare calculated and experimental results.…”

Section: Resultsmentioning

confidence: 99%

Communication: Different behavior of Young's modulus and fracture strength of CeO2: Density functional theory calculations

Sakanoi

Shimazaki

et al. 2014

The Journal of Chemical Physics

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In this Communication, we use density functional theory (DFT) to examine the fracture properties of ceria (CeO 2 ), which is a promising electrolyte material for lowering the working temperature of solid oxide fuel cells. We estimate the stress-strain curve by fitting the energy density calculated by DFT. The calculated Young's modulus of 221.8 GPa is of the same order as the experimental value, whereas the fracture strength of 22.7 GPa is two orders of magnitude larger than the experimental value. Next, we combine DFT and Griffith theory to estimate the fracture strength as a function of a crack length. This method produces an estimated fracture strength of 0.467 GPa, which is of the same order as the experimental value. Therefore, the fracture strength is very sensitive to the crack length, whereas the Young's modulus is not.

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Effect of rare-earth oxides on fracture properties of ceria ceramics

Cited by 77 publications

References 5 publications

Effect of rare earth dopants on structural and mechanical properties of nanoceria synthesized by combustion method

Effect of rare earth dopants on structural and mechanical properties of nanoceria synthesized by combustion method

Determination of Electrochemical Performance and Thermo-Mechanical-Chemical Stability of SOFCs from Defect Modeling

Communication: Different behavior of Young's modulus and fracture strength of CeO2: Density functional theory calculations

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