Effect of chemical redox on Gd-doped ceria mass diffusion

Abstract

Cations’ valence and size influence mass diffusion and oxygen defects in ceria. Mass diffusion is limited by Gd3+ under oxidative conditions, where Ce4+ is the host cation, while it is unleashed under reducing conditions, where Ce3+ and Gd3+ have the same charge and similar size. Solid solutions with enhanced electrochemical properties are formed under controlled thermo-chemical conditions.

Field-Assisted Sintering/Spark Plasma Sintering of Gadolinium-Doped Ceria with Controlled Re-Oxidation for Crack Prevention

“…The appearance of cracks after sintering in Ar-2.9%H 2 atmosphere was successfully suppressed by re-oxidation at 800 °C with feeding synthetic air during the subsequent cooling stage and keeping this temperature for 10 min. This result is in good agreement with the literature, where authors performed free sintering of Ce 0.9 Gd 0.1 O 1.95 in different atmospheres (including re-oxidation) starting from nanometer sized powders [ 20 , 21 , 22 , 23 ]. Thus, the positive effect of re-oxidation on integrity of free sintered GDC10-HP samples was further evidenced.…”

“…The application of a reducing sintering atmosphere instead of air significantly enhances the densification rate and grain growth in GDC. This effect was investigated mainly for H 2 -H 2 O and H 2 -N 2 atmospheres [ 11 , 20 , 21 , 22 ]. In our paper the H 2 -Ar atmosphere was additionally proposed.…”

When two become one: An insight into 2D conductive oxide interfaces

“…For other extrinsic cases such as YSZ and ceria solid solutions the experimental evidences are less clear [61,73,84]. As discussed above, the thickness of the SCL can be reduced by the large concentration of charge carriers, dopants, aliovalent impurities and even the material preparation methods all of which have shown to affect further the profile of the charge carriers' concentration [61,73,85,[93][94][95]. Different profiles of charge concentration are therefore possible to implement and some alternative models have been further considered [73,90].…”

Tuning diffusion paths in shaped ceria nanocrystals

“…Such estimated values are consistent with previous calculations on GDC at the late stage of sintering and indicate that NCs are at least one order of magnitude less diffusive than RDs and NRs. 6,12 Moreover, from the microstructural observations in Fig. 2, the diffusive mechanisms leading to the transition from the specific nanostructured shape to the final sintered grains appear to be controlled by the cubic shape only.…”

“…We especially investigate 10% molar gadolinium-doped ceria (GDC) for its relevance in several chemical, environmental and energy technologies, and for the knowledge gathered on its diffusion effects. [11][12][13][14][15][16] For the morphologies, we synthesized GDC as nanocubes (NCs) and nanorods (NRs) by hydrothermal synthesis, and random spherical nanoparticles (RDs) were obtained by co-precipitation. The chemical methods are described in detail in ref.…”