Investigation of the sintering mechanisms of GDC pellets obtained by the compaction of nanostructured oxide microspheres

Abstract

International audienceThe sintering behavior of green pellets obtained from nanostructured Ce0.8Gd0.2O1.9 submillimetric microspheres is studied in the present paper. Corresponding shrinkage rate curve shows a two-step densification in dynamic conditions, with the presence of two successive extrema, at 1200 K and 1500 K. To fully understand this non-common densification behavior, an iterative study was performed. Multiple characterizations point out multiscale organization of the matter with temperature giving rise to differential sintering stages of two different particle size classes. Concerning 1200 K-first shrinkage rate maximum, it corresponds to the densification of nanometric aggregates of crystallites into submicrometric pre-sintered aggregates, resulting in a specific porous microstructure with residual open porosity. As-generated porosity combined with submicron size of pre-sintered aggregates thus prevent from a homogeneous sintering illustrated by a single maximum shrinkage rate. Finally, the second maximum shrinkage rate at 1500 K can then be associated to optimal temperature for submicrometric particles sintering

Rational synthesis of 10GDC electrolyte through a microwave irradiation GNP facile route for SOFC applications

“…31 The Archimedes's density (Table 2) of the sintered pellets at 800-1200 C is found to be approximately similar to the standard value and to that reported previously. 1,25,32,33 Fig. 3 shows the HR-TEM images of the 10GDC sample sintered at 1200 C for 4 h in the microwave furnace.…”

“…The results of the surface area analysis show good consistency with the data reported elsewhere. 31,32,34 From the nitrogen adsorption analysis, the average pore radius for the sample sintered at 1200 C is estimated to be 3.1203 nm with an average particle size of 10.50 nm, was calculated using eqn (1). The comparison of the particle size determined by the XRD method d(hkl) or d(BET) indicates an increase in the extent of agglomeration during microwave irradiation.…”

Development of Highly Nano-Dispersed NiO/GDC Catalysts from Ion Exchange Resin Templates

“…In all catalysts, a first set of peaks could be observed, which can be attributed to a single crystal fluorite-type structure with a lattice parameter between 5.4235 and 5.4280 Å . This value is higher than that for CeO2 (5.411 Å [15]), which could be attributed to the substitution of CeO2 by Gd2O3 in the catalyst support [12,16]. These results, together with the previous ICP-AES analysis (Figure 1), confirm not only the presence of Gd in the structure of the materials, but also that the calcination procedure achieved a solid solution between Ce and Gd oxides, leading to a GDC material with a Ce/Gd ratio of ~3-4 depending on the sample (Figure 1b).…”

“…In all catalysts, a first set of peaks could be observed, which can be attributed to a single crystal fluorite-type structure with a lattice parameter between 5.4235 and 5.4280 Å. This value is higher than that for CeO 2 (5.411 Å [15]), which could be attributed to the substitution of CeO 2 by Gd 2 O 3 in the catalyst support [12,16]. TGA results [11,13] (see Supplementary Materials for detailed calculation).…”

Development of a processing map for safe flash sintering of gadolinium‐doped ceria

“…. To a limited degree, thereduction of sintering temperature can be achieved by reducing the particle size 19,20 , adding sintering aids 21,22 or processing under reducing atmosphere [23][24][25] . But nano-sized…”