Transition between two solid‐solutions: Effective and easy way for fine Ce_1−xGd_xO_2−x/2 powders preparation

Abstract

Ceria, pure or doped, is an important electrolyte material in solid oxide fuel cells, catalysts, and plutonium surrogates. Even though ceria is a widely studied material, its coprecipitation with the most common doping element, gadolinium, remains mostly overlooked. Here, we present a comprehensive study of gadolinium–cerium oxalates prepared by coprecipitation of gadolinium (III) and cerium (III) salts by oxalic acid under different reaction conditions and element ratios. For this purpose, we assessed the effects of basic precipitation conditions on the final oxalate size, shape, and conversion into the corresponding oxides. The results showed that coprecipitation with oxalic acid yields and ideal solid solution, which translates into the oxides. This low‐cost and straightforward synthetic route provides then high‐quality solid solutions of Ge–Gd in the oxide lattice. Thus, this approach has a high industrialization potential, with significant advantages over hydrolysis or hydrothermal techniques.

Processing, Phase Stability, and Conductivity of Multication-Doped Ceria

“…), co-precipitation using oxalic acid as the precipitating agent is a particularly effective method to reduce segregation [11]. The oxalate method produces nanocrystalline single-phase precipitates that are already mixed for the lanthanide elements [12]. All lanthanide oxalates form in the P2 1 /c space group, allowing a single-phase precipitate to be formed during the synthesis method.…”

Hydrothermal conversion of cerium oxalate to CeO2: a parade of oxalate and water coordination modes

“…5–10 This is one of the main differences with thermal conversion, during which the initial oxalate shape is retained. 1,3,23,24…”

“…Oxalates are low-cost, simple, but essential species in the chemistry of transition metals, lanthanides, 1 and actinides. 2 Thanks to the low solubility of oxalate salts, oxalic acid is used: as a separation agent of metal ions from aqueous solutions; as a ligand in coordination compounds; in metal-organic frameworks.…”

“…Pure and mixed oxalates were prepared by heterogeneous precipitation as detailed previously 1,23 (a description is in the ESI †). Briefly, for the hydrothermal conversion, 250 mg (0.35 mmol) of Ce 2 (C 2 O 4 ) 3 Á10H 2 O or Ce 1Àx Gd x (C 2 O 4 ) 3 Á10H 2 O (x = 0.1, 0.2, 0.3) was placed in a Teflont-lined autoclave (capacity of 50 mL) together with distilled water (21 mL) or nitric acid solution of the desired pH.…”

“…[5][6][7][8][9][10] This is one of the main differences with thermal conversion, during which the initial oxalate shape is retained. 1,3,23,24 Recrystallisation was also studied from the crystallographic viewpoint. The PXRD patterns of selected samples were plotted (Fig.…”