Grain Growth of Micron-Sized Grains in Undoped and Cobalt Oxide Doped Ceria Solid Solutions

Abstract

Isothermal grain growth experiments have been conducted for undoped as well as cobalt oxide doped CeO 2 and Ce 0.8 Gd 0.2 O 1.9 CGO20 . Due to the solute drag effect of the dissolved gadolinium ions, the grain boundary mobility of CGO20 was significantly lower than that one of CeO 2 . The addition of cobalt oxide increases the grain boundary mobility of CGO20. This increase is assigned to the formation of a characteristic cobalt oxide rich grain boundary film. In undoped and cobalt oxide doped CGO20, a transition from regular grain growth at high temperature in micron-sized grains to self-limited grain growth at low temperature in nanometer-sized grains occurs. As a consequence, highly stable microstructures result at lower temperatures. It is suggested that strain in amorphous grain boundary films becomes important for the self limited grain growth for very small grains at low temperatures.

Effect of specific surface area on syngas production performance of pure ceria in high-temperature thermochemical redox cycling coupled to methane partial oxidation

“…3b, the grain sizes did not markedly increase during a heating time of t ¼ 1/60 to 50 h around T ¼ 1173 K in the heating experiment without syngas production. These experimental results observed with XRD are available in the estimation of sintering extent in a late period with heating time from $2 to $100 h. [27][28][29]35 The familiar grain growth equation in the late period is expressed by:…”

“…Sintering mechanism of pure and doped ceria under high temperatures without syngas production has been reported in the literatures. [22][23][24][25][26][27][28][29][30][31][32][33] In this study, we experimentally investigate the effect of specic surface area on syngas production of pure ceria powders during heating without syngas production (further referred to as heating experiments) and during an isothermal MPO-CDS thermochemical redox cycling (further referred to as cycling experiments). The temperatures are varied in the range 973-1773 K in the heating experiments, whereas the reduction and oxidation temperatures are xed at 1173 K in the cycling experiments.…”

The Effect of Cobalt Oxide Addition on the Conductivity of Ce0.9Gd0.1O1.95

“…Our recent sintering and grain growth studies of cobalt oxide doped CGO20 suggested that cobalt oxide doping acts as an activator material [20,21]. Activated sintering has extensively been described for the case of Bi 2 O 3 -doped ZnO and manifests itself mainly in increased shrinkage rates below the eutectic temperature combined with intergranular films [22].…”

Time–Temperature–Transformation (TTT) Diagrams for Crystallization of Metal Oxide Thin Films

“…Recently, amorphous metal oxide thin fi lms have been reported to exhibit similar crystallization kinetic rules and characteristics as glass-based systems, [ 13 ] for instance, Kissinger crystallization activation energies between 1-3 eV, [ 14 ] JohnsonMehl-Avrami characteristics, [ 15 , 16 ] and crystallization enthalpies around 90-100 J g −1 .…”