Oxygen ion conductivity in ceria-based electrolytes co-doped with samarium and gadolinium

Coles-Aldridge, Alice V.; Baker, Richard T.

doi:10.1016/j.ssi.2020.115255

Cited by 23 publications

(24 citation statements)

References 46 publications

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“…Lanthanide-doped ceria-based electrolytes display high ionic conductivities at these temperatures and have been used successfully in the manufacture of SOFCS [7,8]. Gadolinium and samarium are the most common dopants used in ceria electrolytes, as they give rise to some of the highest conductivities, an order of magnitude higher than for YSZ at 600 • C [6,9]. Despite the success of these materials, clearly there is still an advantage in developing materials with even higher conductivity to either reduce operating temperatures or increase power output.…”

Section: Introductionmentioning

confidence: 99%

Effects of Strontium Content on the Microstructure and Ionic Conductivity of Samarium-Doped Ceria

Sherwood

Baker

2021

Solids

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Due to its high oxygen ion conductivity at elevated temperatures, samarium-doped ceria (SDC) is a very promising material for application in solid state electrochemical devices and especially in the electrolytes of solid oxide fuel cells. Several prior studies have reported a further improvement in the ionic conductivity of SDC on doping with small amounts of strontium. It is suggested that strontium acts as a sintering aid—improving the microstructure of SDC—and as a scavenger of silicon impurities, decreasing its tendency to form resistive phases at grain boundaries. However, because of the range of preparation methods and the resulting differences in microstructure and silicon levels, some inconsistencies exist in the literature. Furthermore, the effect of strontium on the intrinsic (bulk) conductivity of SDC is not often discussed. To address these issues, a systematic, combined microstructural and conductivity study has been performed on a compositional series with a range of strontium contents, Ce0.8−xSm0.2SrxO2−δ (x = 0, 0.002, 0.005, 0.01, 0.02, 0.03, 0.04). A low temperature synthesis affording products with low silicon was employed. Total bulk and grain boundary conductivity data were obtained over a wide temperature range. Increasing strontium content caused a general decrease in total and intrinsic conductivity, but there was an improvement in grain boundary conductivity at the lowest strontium levels. These results were interpreted by reference to the microstructures using, among other parameters, the blocking, and normalised blocking, factors.

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Section: Introductionmentioning

confidence: 99%

Effects of Strontium Content on the Microstructure and Ionic Conductivity of Samarium-Doped Ceria

Sherwood

Baker

2021

Solids

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“…Figures 1 -4 compare the trends in the variation of the lattice parameter as a function of the samarium mole fraction in the computational results obtained in this work and the experimental results obtained in (5). When constructing these figures, the experimental data was assumed to be identical for both DSα and DSβ doping strategies.…”

Section: Resultsmentioning

confidence: 96%

“…Such a supercell would consist of 8 ceria unit cells (or minicubes). In line with (5), two compositional series of doped ceria were modelled. Series 1.…”

Section: The Compositional Seriesmentioning

confidence: 99%

Computational Modelling of Ceria-Based Solid Oxide Fuel Cell Electrolyte Materials

et al. 2021

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A simulation methodology for calculating the lattice parameter and oxygen ion migration energy of ceria-based electrolyte formulations is devised. The results are analysed and benchmarked against experimentally obtained values to verify the efficacy of the simulation methodology. A total of 26, 2 x 2 x 2 samarium (Sm)and gadolinium (Gd)-doped supercells of different compositions and doping profiles were modelled and simulated by molecular mechanics force field methods using CP2K. The results of the computational simulations are comparable with those obtained experimentally, especially when there are equal amounts of Sm and Gd dopants in the structure. Simulation results can also provide insights into the mechanisms of ionic conduction. The incongruence of the computational and experimental results is attributed to the limitations of the molecular mechanics force field methodology utilised, with the expectation that an ab initio density functional theory (DFT) calculation would yield closer conformance.

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“…However, there is interest in whether doping with multiple elements may be beneficial and whether it could lead to materials with higher ionic conductivities than the best singly doped materials. For example, recent studies on the multiple doping of multiple lanthanides gave promising results, especially for Sm and Gd [11,12]. The present study looks specifically at the effects of co-doping Sr and Sm in ceria.…”

Section: Introductionmentioning

confidence: 97%

Effects on Microstructure and Ionic Conductivity of the Co-Doping with Strontium and Samarium of Ceria with Constant Oxygen Vacancy Concentration

Sherwood

Baker

2021

Solids

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Partially substituted cerias are attractive materials for use as electrolytes in intermediate-temperature solid oxide fuel cells (SOFCs). Ceria doped with Sm or Gd has been found to have high ionic conductivities. However, there is interest in whether doping with multiple elements could lead to materials with higher ionic conductivities. The present study looks at the effects of co-doping Sr and Sm in ceria. A compositional series, Ce0.8+xSm0.2−2xSrxO2−δ (with x = 0–0.08), designed to have a constant oxygen vacancy concentration, was successfully prepared using the citrate–nitrate complexation method. A solubility limit of ~5 cation% Sr was found to impact material structure and conductivity. For phase-pure materials, with increasing Sr content, sinterability increased slightly and intrinsic conductivity decreased roughly linearly. The grain boundaries of phase-pure materials showed only a very small blocking effect, linked to the high-purity synthesis method employed, while at high %Sr, they became more blocking due to the presence of a SrCeO3 impurity. Grain capacitances were found to be 50–60 pF and grain boundary capacitances, 5–50 nF. The variation in the bulk capacitance with Sr content was small, and the variation in grain boundary capacitance could be explained by the variation in grain size. Slight deviations at high %Sr were attributed to the SrCeO3 impurity. In summary, in the absence of deleterious effects due to poor microstructure or impurities, such as Si, there is no improvement in conductivity on co-doping with Sr and Sm.

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Oxygen ion conductivity in ceria-based electrolytes co-doped with samarium and gadolinium

Cited by 23 publications

References 46 publications

Effects of Strontium Content on the Microstructure and Ionic Conductivity of Samarium-Doped Ceria

Effects of Strontium Content on the Microstructure and Ionic Conductivity of Samarium-Doped Ceria

Computational Modelling of Ceria-Based Solid Oxide Fuel Cell Electrolyte Materials

Effects on Microstructure and Ionic Conductivity of the Co-Doping with Strontium and Samarium of Ceria with Constant Oxygen Vacancy Concentration

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