Long-term structural surface modifications of mixed conducting La2NiO4+δ at high temperatures

Long-term annealing of La 2 NiO 4+δ single crystals at 1,273 K in air leads to the formation of nickel-rich Ruddlesden–Popper phases at the single-crystal surfaces. Both the composition and the morphology of these phases depend on the surface orientation; whereas only crystallites of La 4 Ni 3 O 10−...

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Bibliographic Details
Published in:Monatshefte für Chemie 2009-09, Vol.140 (9), p.1095-1102
Main Authors: Gauquelin, Nicolas, Weirich, Thomas E., Ceretti, Monica, Paulus, Werner, Schroeder, Michael
Format: Article
Language:English
Subjects:
Analytical Chemistry
Chemical Sciences
Chemistry
Chemistry and Materials Science
Chemistry/Food Science
Inorganic Chemistry
Material chemistry
Organic Chemistry
Original Paper
Physical Chemistry
Theoretical and Computational Chemistry
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Summary:Long-term annealing of La 2 NiO 4+δ single crystals at 1,273 K in air leads to the formation of nickel-rich Ruddlesden–Popper phases at the single-crystal surfaces. Both the composition and the morphology of these phases depend on the surface orientation; whereas only crystallites of La 4 Ni 3 O 10−δ were observed on (001) surfaces, both La 3 Ni 2 O 7−δ and La 4 Ni 3 O 10−δ were formed on (100) surfaces. The formation of the nickel-rich RP phases is believed to be due to surface segregation of nickel or evaporation of a volatile lanthanum species. The crystallographic (001) planes inside the La 3 Ni 2 O 7−δ and La 4 Ni 3 O 10−δ crystallites were found to be oriented in the direction of preferential crystallite growth, which indicates that the diffusion of lanthanum and nickel cations is faster along the crystallographic (001) planes than perpendicular to these planes. Graphical abstract
ISSN:0026-9247
1434-4475
DOI:10.1007/s00706-009-0146-2