Flash-Sintering and Characterization of La0.8Sr0.2Ga0.8Mg0.2O3-δ Electrolytes for Solid Oxide Fuel Cells

Sun, Kening; Jiang, Taizhi; Qiao, Jinshuo; Sun, Wang; Rooney, David; Wang, Zhenhua

doi:10.1016/j.electacta.2016.02.207

Cited by 36 publications

(13 citation statements)

References 53 publications

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“…As was mentioned earlier, a few atomic layers softened/melted nanoparticle surfaces have a transient character; hence, melted residue in pure oxides can barely be observed. Nevertheless, melting at the microcrystal surfaces or at the grain boundaries where melting led to compositional 43,44 or morphological 2,[45][46][47] changes during the SPS/flash sintering were reported.…”

Section: The Percolation Modelmentioning

confidence: 99%

Flash sintering of dielectric nanoparticles as a percolation phenomenon through a softened film

Chaim

Chevallier

Weibel

et al. 2017

Journal of Applied Physics

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Recent work [Biesuz et al., J. Appl. Phys. 120, 145107 (2016)] showed analogies between the flash sintering and dielectric breakdown in a-aluminas pre-sintered to different densities. Here, we show that flash sintering of dielectric nanoparticles can be described as a universal behavior by the percolation model. The electrical system is composed of particles and their contact point resistances, the latter softened first due to preferred local Joule heating and thermal runaway during the flash. Local softening has a hierarchical and invasive nature and propagates between the electrodes. The flash event signals the percolation threshold by invasive nature of the softened layer at the particle surfaces. Rapid densification is associated with local particle rearrangements due to attractive capillary forces induced by the softened film at the particle contacts. Flash sintering is a critical phenomenon with a self-organizing character. The experimental electric conductivity results from flash sintering are in full agreement with those calculated from the percolation model.

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Section: The Percolation Modelmentioning

confidence: 99%

Flash sintering of dielectric nanoparticles as a percolation phenomenon through a softened film

Chaim

Chevallier

Weibel

et al. 2017

Journal of Applied Physics

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“…The mechanisms that occur during flash are still under debate, although certainly, samples show a dramatic increase of both temperature and conductivity during the flash event and less dramatically, in a premonitory period before the onset of flash. The increase in conductivity is electronic in nature and the associated increase in sample temperature is attributed to Joule heating . What is unclear is whether additional changes in intrinsic properties of the material occur in response to the bias, leading to an enhanced Joule heating effect, rapid sintering, and associated luminescence; however, there continues to be a debate as to whether electroluminescence occurs or whether the observed luminescence is caused by black‐body radiation …”

Section: Introductionmentioning

confidence: 99%

Induced p‐type semiconductivity in yttria‐stabilized zirconia

Vendrell

West

2019

J Am Ceram Soc

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8 mol% yttria‐stabilized zirconia (8YSZ) ceramic is an oxide ion conductor at atmospheric pressure but shows the onset of p‐type semiconduction, in addition to the preexisting oxide ion conduction, on application of a dc bias in the range 4‐66 Vcm−1 and at temperatures in the range 150°C‐750°C. The p‐type behavior is attributed to the location and hopping of holes on oxygen. This contrasts with the commonly observed introduction of n‐type conduction under reducing conditions and high fields. The hole conductivity increases with both dc bias and pO2. Its occurrence may contribute to the early stages of flash phenomena in 8YSZ ceramics.

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“…Although various electrolyte materials have been discovered following this line, there have been no alternative materials so far. Doped ceria possesses excellent O 2− conductivity (0.1 S cm −1 ) under 800 °C, 200 °C below than that of the YSZ [10,11,12]. However, the electronic conduction characteristic, owing to the Ce 4+ to Ce 3+ reduction in fuel cell operation, leading to losses for open circuit voltage (OCV) of the SOFC with doped ceria electrolytes [13].…”

Section: Introductionmentioning

confidence: 99%

Semiconductor-Ionic Nanocomposite La0.1Sr0.9MnO3−δ-Ce0.8Sm0.2O2−δ Functional Layer for High Performance Low Temperature SOFC

Wang

et al. 2018

Materials

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A novel composite was synthesized by mixing La0.1Sr0.9MnO3−δ (LSM) with Ce0.8Sm0.2O2−δ (SDC) for the functional layer of low temperature solid oxide fuel cell (LT-SOFC). Though LSM, a highly electronic conducting semiconductor, was used in the functional layer, the fuel cell device could reach OCVs higher than 1.0 V without short-circuit problem. A typical diode or rectification effect was observed when an external electric force was supplied on the device under fuel cell atmosphere, which indicated the existence of a junction that prevented the device from short-circuit problem. The optimum ratio of LSM:SDC = 1:2 was found for the LT-SOFC to reach the highest power density of 742 mW·cm−2 under 550 °C The electrochemical impedance spectroscopy data highlighted that introducing LSM into SDC electrolyte layer not only decreased charge-transfer resistances from 0.66 Ω·cm2 for SDC to 0.47–0.49 Ω·cm2 for LSM-SDC composite, but also decreased the activation energy of ionic conduction from 0.55 to 0.20 eV.

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Flash-Sintering and Characterization of La0.8Sr0.2Ga0.8Mg0.2O3-δ Electrolytes for Solid Oxide Fuel Cells

Cited by 36 publications

References 53 publications

Flash sintering of dielectric nanoparticles as a percolation phenomenon through a softened film

Flash sintering of dielectric nanoparticles as a percolation phenomenon through a softened film

Induced p‐type semiconductivity in yttria‐stabilized zirconia

Semiconductor-Ionic Nanocomposite La0.1Sr0.9MnO3−δ-Ce0.8Sm0.2O2−δ Functional Layer for High Performance Low Temperature SOFC

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