Gadolinium-doped ceria

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Gadolinium-doped ceria (GDC) (known alternatively as gadolinia-doped ceria, gadolinium-doped cerium oxide (GCO), cerium-gadolinium oxide (CGO), or cerium(IV) oxide, gadolinium-doped, formula Gd:CeO2) is a ceramic electrolyte used in solid oxide fuel cells (SOFCs). It has a cubic structure and a density of around 7.2 g/cm3 in its oxidised form. [1] It is one of a class of ceria-doped electrolytes with higher ionic conductivity and lower operating temperatures (<700 °C) than those of yttria-stabilized zirconia, [2] the material most commonly used in SOFCs. Because YSZ requires operating temperatures of 800–1000 °C to achieve maximal ionic conductivity, the associated energy and costs make GDC a more optimal (even "irreplaceable", [3] according to researchers from the Fraunhofer Society) material for commercially viable SOFCs.

Contents

Structure and properties

Oxygen vacancies are created when gadolinium (a trivalent cation) is introduced into ceria (CeO2, with Ce in the 4+ oxidation state) or on reduction in CO or H2. [1] The high concentration and mobility of the oxide ion vacancies results in a high ionic conductivity in this material. In addition to its high ionic conductivity GDC is an attractive alternative to YSZ as an electrolyte due to low reactivity and good chemical compatibility with many mixed conducting cathode materials. [4] Dopant levels of Gd typically range from 10% to 20%. The majority of SOFC researchers and manufacturers still favor the use of YSZ over CGO due to YSZ having superior strength and because GDC will reduce at high temperature when exposed to H2 or CO. [1]

Synthesis

Methods of synthesis have included precipitation, [5] hydrothermal treatment, sol-gel, spray pyrolysis technique (SPT), [6] combustion [7] and nanocasting [8] using cerium sources such as cerium nitrate, ceric ammonium nitrate, [9] cerium oxalate, cerium carbonate and cerium hydroxide. [8] GDC has been synthesized in such forms as powder, ink, discs, and nanomaterials (including nanoparticle, nanocrystals, nanopowder, and nanowires). [10]

Applications

Aside from SOFCs, GDC has other uses:

See also

Related Research Articles

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<span class="mw-page-title-main">Strontium titanate</span> Chemical compound

Strontium titanate is an oxide of strontium and titanium with the chemical formula SrTiO3. At room temperature, it is a centrosymmetric paraelectric material with a perovskite structure. At low temperatures it approaches a ferroelectric phase transition with a very large dielectric constant ~104 but remains paraelectric down to the lowest temperatures measured as a result of quantum fluctuations, making it a quantum paraelectric. It was long thought to be a wholly artificial material, until 1982 when its natural counterpart—discovered in Siberia and named tausonite—was recognised by the IMA. Tausonite remains an extremely rare mineral in nature, occurring as very tiny crystals. Its most important application has been in its synthesized form wherein it is occasionally encountered as a diamond simulant, in precision optics, in varistors, and in advanced ceramics.

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<span class="mw-page-title-main">Solid oxide fuel cell</span> Fuel cell that produces electricity by oxidization

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Cerium(IV) oxide, also known as ceric oxide, ceric dioxide, ceria, cerium oxide or cerium dioxide, is an oxide of the rare-earth metal cerium. It is a pale yellow-white powder with the chemical formula CeO2. It is an important commercial product and an intermediate in the purification of the element from the ores. The distinctive property of this material is its reversible conversion to a non-stoichiometric oxide.

<span class="mw-page-title-main">Bismuth(III) oxide</span> Chemical compound

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CGO may refer to:

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<span class="mw-page-title-main">Solid oxide electrolyzer cell</span> Type of fuel cell

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<span class="mw-page-title-main">Solid state ionics</span>

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<span class="mw-page-title-main">Cerium(III) acetylacetonate</span> Chemical compound

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<span class="mw-page-title-main">Gadolinium acetylacetonate</span> Chemical compound

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<span class="mw-page-title-main">Samarium(III) nitrate</span> Chemical compound

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References

  1. 1 2 3 Badwal, S. P. S.; Fini, D.; Ciacchi, F. T.; Munnings, C.; Kimpton, J. A.; Drennan, J. (2013). "Structural and microstructural stability of ceria – gadolinia electrolyte exposed to reducing environments of high temperature fuel cells". Journal of Materials Chemistry A. 1 (36): 10768. doi:10.1039/c3ta11752a.
  2. ↑ "Gadolinia doped Ceria GDC | AMERICAN ELEMENTS ® Supplier & Info". Americanelements.com. 2010-08-24. Retrieved 2013-08-16.
  3. ↑ "Publica". Publica.fraunhofer.de. Retrieved 2013-08-16.
  4. ↑ Garche, Jurgen. et al., ed. Encyclopedia of Electrochemical Power Sources. Oxford: Newnes, 2009.
  5. ↑ "Comparative Study for Average Crystallite Size of gadolinium doped-ceria synthesized by different methods" (PDF). Sbpmat.org.br. Retrieved 2013-08-16.
  6. ↑ "Fabrication of 10%Gd-doped ceria (GDC)/NiO-GDC half cell for low or intermediate temperature solid oxide fuel cells using spray pyrolysis" . Retrieved 2013-08-16.
  7. ↑ Luo, Dan; Luo, Zhongyang; Yu, Chunjiang; Cen, Kefa (2007). "Study on Agglomeration and Densification Behaviors of Gadolinium-Doped Ceria Ceramics". Journal of Rare Earths. 25 (2): 163–167. doi:10.1016/S1002-0721(07)60066-0.
  8. 1 2 Rossinyol, Emma, et al. "Gadolinium Doped Ceria Nanocrystals Synthesized From Mesoporous Silica." J Nanopart Res (2008) 10:369–375 doi : 10.1007/s11051-007-9257-z
  9. ↑ Halmenschlager, C. M.; Neagu, R.; Rose, L.; Malfatti, C. F.; Bergmann, C. P. (2013-02-01). "Influence of the process parameters on the spray pyrolysis technique, on the synthesis of gadolinium doped-ceria thin film". Materials Research Bulletin. 48 (2): 207–213. doi:10.1016/j.materresbull.2012.09.073. ISSN   0025-5408.
  10. ↑ Bocchetta, Patrizia; Santamaria, Monica; Di Quarto, Francesco (2012). "Electrodeposition of Supported Gadolinium-Doped Ceria Solid Solution Nanowires". Journal of the Electrochemical Society. Jes.ecsdl.org. 159 (5): E108–E114. doi:10.1149/2.005206jes.
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