Densification and grain growth behavior study of trivalent MO1.5 (M=Gd, Bi) doped ceria systems

Computational Study of Cation Diffusion in Ceria

“…Large, positive values of Δ S mig (>25 k B ) would improve the agreement, but they would not affect the activation enthalpies of diffusion. Moreover, a strong impact on the diffusion coefficients is not expected, since activation entropies of migration are generally of the order of several k B . , Lastly, regarding the activation enthalpy of bulk diffusion, there is closer agreement between our predicted value of Δ H D (V Ce ⁗ ) = 8.44 eV and the values of (7.5 ± 0.5) eV derived from grain growth studies. − Such studies, however, only probe diffusion indirectly, relying on the model being applicable to the experimental data. In addition, the absolute magnitude of the experimental bulk diffusion coefficients was not derived, so it is unclear whether these values are physically reasonable.…”

“…Third, indirect examination of cation diffusion in pure and doped ceria polycrystals (by studying grain-growth kinetics − ) yields even higher values for Δ H D . In those studies in which bulk diffusion was concluded to govern grain growth, − the activation enthalpy of the growth kinetics was generally in the range of (7.5 ± 0.5) eV. Fourth, the only computational study of cation migration in CeO 2 gives migration enthalpies of Δ H mig,V = 5.3 eV for the vacancy mechanism (and Δ H mig,i = 6.1 eV for the interstitial mechanism), and these are in the same range as the experimentally determined values − of the enthalpy of diffusion.…”

“…Second, these experiments yield enthalpies of diffusion, Δ H D , that vary significantly, from 5.0 to 6.7 eV (refs − ). Third, indirect examination of cation diffusion in pure and doped ceria polycrystals (by studying grain-growth kinetics − ) yields even higher values for Δ H D . In those studies in which bulk diffusion was concluded to govern grain growth, − the activation enthalpy of the growth kinetics was generally in the range of (7.5 ± 0.5) eV.…”

Kissinger-Style Kinetic Analysis for Sintering Dilatometry Data

“…Figure 4: Shrinkage rate data for sintering of Gd doped ceria obtained from Banerjee et al [57] (a), with the densification rate peaks shown by the black arrows, and Kissinger-style analysis of the densification peaks (b) Guan et al studied gadolinium doped ceria with and without the addition of bismuth [57] . The [57]…”

The influence of co-sintering Bi2O3 on Yb0.2Ce0.8O2-δ ceramic SOFC

“…Solid state reaction method has advantage easy to construct stoichiometry and relatively inexpensive method [17]. By contrast, the solid-state reaction method has disadvantage needs hightemperature process [10,18]. Natural sintering of ytterbium doped cerium (YBDC) needs a high temperature (1500-1700 °C), to lower sintering temperature commonly use co-sintering such as Bi2O3 [19][20].…”