Effect of transition metal oxides on densification and electrical properties of Si-containing Ce0.8Gd0.2O 2-δ ceramics

T. S. Zhang, J. Ma, Yongjun Leng, S. H. Chan, P. Hing, J. A. Kilner

    Research output: Contribution to journalArticle

    131 Citations (Scopus)

    Abstract

    Ce0.8Gd0.2O2-δ (CGO20) ceramic has been considered as one of the most promising electrolytes for intermediate temperature (IT) fuel cells. It has been reported that some transition metal oxides (TMO), such as MnO2, Fe2O3 and Co 3O4, are effective sintering aids for the densification of ceria-based electrolytes. However, very little information is available regarding the effect of TMO addition on the electrical properties of Si-containing CGO20 ceramics. In this study, 0.5 at.% (atomic percent) TMOs have been loaded into the CGO20 with ∼30 ppm (pure) and ∼200 ppm (impure) SiO2, respectively, and the sintering behavior and ionic conductivity have been investigated. It has been found that Co3O4 is the most effective sintering aid, and the sintering temperature of CGO20 can be reduced by over 200 °C by adding 0.5 at.% CoO4/3. All the TMOs used show a slight effect on the grain-boundary (GB) conductivity of the pure CGO20. However, SiO2 additions, together with MnO2 and Co3O4, have found to be extremely detrimental to the GB conduction of CGO20. As compared to the impure CGO20, the GB resistance has been increased by over six times for the impure one with addition of only 0.5 at.% CoO4/3. On the other hand, in contrast to the Mn or Co doping case, small addition of Fe2O3 has a scavenging effect on SiO2 impurity, and significantly improves the GB conduction of the impure CGO20. Therefore, Fe2O3 could be used as an effective sintering aid, as well as a grain-boundary scavenger for SiO 2 contaminated ceria-based electrolytes.

    Original languageEnglish (US)
    Pages (from-to)187-195
    Number of pages9
    JournalSolid State Ionics
    Volume168
    Issue number1-2
    DOIs
    StatePublished - Mar 15 2004

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    densification
    Densification
    Oxides
    Transition metals
    metal oxides
    sintering
    Grain boundaries
    Electric properties
    Sintering
    grain boundaries
    transition metals
    electrical properties
    ceramics
    Electrolytes
    Cerium compounds
    electrolytes
    conduction
    conductivity
    Scavenging
    scavenging

    All Science Journal Classification (ASJC) codes

    • Chemistry(all)
    • Materials Science(all)
    • Condensed Matter Physics

    Cite this

    Zhang, T. S. ; Ma, J. ; Leng, Yongjun ; Chan, S. H. ; Hing, P. ; Kilner, J. A. / Effect of transition metal oxides on densification and electrical properties of Si-containing Ce0.8Gd0.2O 2-δ ceramics. In: Solid State Ionics. 2004 ; Vol. 168, No. 1-2. pp. 187-195.
    @article{c9bc6aa6e21e49ce83e6f016f1b21874,
    title = "Effect of transition metal oxides on densification and electrical properties of Si-containing Ce0.8Gd0.2O 2-δ ceramics",
    abstract = "Ce0.8Gd0.2O2-δ (CGO20) ceramic has been considered as one of the most promising electrolytes for intermediate temperature (IT) fuel cells. It has been reported that some transition metal oxides (TMO), such as MnO2, Fe2O3 and Co 3O4, are effective sintering aids for the densification of ceria-based electrolytes. However, very little information is available regarding the effect of TMO addition on the electrical properties of Si-containing CGO20 ceramics. In this study, 0.5 at.{\%} (atomic percent) TMOs have been loaded into the CGO20 with ∼30 ppm (pure) and ∼200 ppm (impure) SiO2, respectively, and the sintering behavior and ionic conductivity have been investigated. It has been found that Co3O4 is the most effective sintering aid, and the sintering temperature of CGO20 can be reduced by over 200 °C by adding 0.5 at.{\%} CoO4/3. All the TMOs used show a slight effect on the grain-boundary (GB) conductivity of the pure CGO20. However, SiO2 additions, together with MnO2 and Co3O4, have found to be extremely detrimental to the GB conduction of CGO20. As compared to the impure CGO20, the GB resistance has been increased by over six times for the impure one with addition of only 0.5 at.{\%} CoO4/3. On the other hand, in contrast to the Mn or Co doping case, small addition of Fe2O3 has a scavenging effect on SiO2 impurity, and significantly improves the GB conduction of the impure CGO20. Therefore, Fe2O3 could be used as an effective sintering aid, as well as a grain-boundary scavenger for SiO 2 contaminated ceria-based electrolytes.",
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    Effect of transition metal oxides on densification and electrical properties of Si-containing Ce0.8Gd0.2O 2-δ ceramics. / Zhang, T. S.; Ma, J.; Leng, Yongjun; Chan, S. H.; Hing, P.; Kilner, J. A.

    In: Solid State Ionics, Vol. 168, No. 1-2, 15.03.2004, p. 187-195.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - Effect of transition metal oxides on densification and electrical properties of Si-containing Ce0.8Gd0.2O 2-δ ceramics

    AU - Zhang, T. S.

    AU - Ma, J.

    AU - Leng, Yongjun

    AU - Chan, S. H.

    AU - Hing, P.

    AU - Kilner, J. A.

    PY - 2004/3/15

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    AB - Ce0.8Gd0.2O2-δ (CGO20) ceramic has been considered as one of the most promising electrolytes for intermediate temperature (IT) fuel cells. It has been reported that some transition metal oxides (TMO), such as MnO2, Fe2O3 and Co 3O4, are effective sintering aids for the densification of ceria-based electrolytes. However, very little information is available regarding the effect of TMO addition on the electrical properties of Si-containing CGO20 ceramics. In this study, 0.5 at.% (atomic percent) TMOs have been loaded into the CGO20 with ∼30 ppm (pure) and ∼200 ppm (impure) SiO2, respectively, and the sintering behavior and ionic conductivity have been investigated. It has been found that Co3O4 is the most effective sintering aid, and the sintering temperature of CGO20 can be reduced by over 200 °C by adding 0.5 at.% CoO4/3. All the TMOs used show a slight effect on the grain-boundary (GB) conductivity of the pure CGO20. However, SiO2 additions, together with MnO2 and Co3O4, have found to be extremely detrimental to the GB conduction of CGO20. As compared to the impure CGO20, the GB resistance has been increased by over six times for the impure one with addition of only 0.5 at.% CoO4/3. On the other hand, in contrast to the Mn or Co doping case, small addition of Fe2O3 has a scavenging effect on SiO2 impurity, and significantly improves the GB conduction of the impure CGO20. Therefore, Fe2O3 could be used as an effective sintering aid, as well as a grain-boundary scavenger for SiO 2 contaminated ceria-based electrolytes.

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