Exsolution of Embedded Nanoparticles in Defect Engineered Perovskite Layers

ACS Nano, vol. 15, pp. 4546–4560

Abstract

Exsolution phenomena are highly debated as efficient synthesis routes for nanostructured composite electrode materials for the application in solid oxide cells (SOCs) and the development of next-generation electrochemical devices for energy conversion. Utilizing the instability of perovskite oxides, doped with electrocatalytically active elements, highly dispersed nanoparticles can be prepared at the perovskite surface under the influence of a reducing heat treatment. For the systematic study of the mechanistic processes governing metal exsolution, epitaxial SrTi 0.9 Nb 0.05 Ni 0.05 O 3-δ thin films of well-defined stoichiometry are synthesized and employed as model systems to investigate the interplay of defect structures and exsolution behavior. Spontaneous phase separation and the formation of dopant-rich features in the as-synthesized thin film material is revealed by high-resolution transmission electron microscopy (HR-TEM) investigations. The resulting nanostructures are enriched by nickel and serve as preformed nuclei for the subsequent exsolution process under reducing conditions, which reflects a so far unconsidered process drastically affecting the understanding of nanoparticle exsolution phenomena. Using an approach of combined morphological, chemical, and structural analysis of the exsolution response, a limitation of the exsolution dynamics for nonstoichiometric thin films is found to be correlated to a distortion of the perovskite host lattice. Consequently, the incorporation of defect structures results in a reduced particle density at the perovskite surface, presumably by trapping of nanoparticles in the oxide bulk.

Authors 9

1. Moritz Lukas Weber corresponding Aachen Institute of Mineral Engineering (GHI)

   Forschungszentrum Jülich · Jülich Aachen Research Alliance · RWTH Aachen University

   Affiliation as printed

   Institute of Energy and Climate Research (IEK-1), Forschungszentrum Juelich GmbH, 52425 Juelich, Germany

   Institute of Mineral Engineering (GHI), RWTH Aachen University, 52062 Aachen, Germany

   Juelich-Aachen Research Alliance (JARA-FIT), 52425 Juelich, Germany

   Peter Gruenberg Institute (PGI-7), Forschungszentrum Juelich GmbH, 52425 Juelich, Germany

2. Marek Wilhelm

   Forschungszentrum Jülich

   Affiliation as printed

   Peter Gruenberg Institute (PGI-6), Forschungszentrum Juelich GmbH, 52425 Juelich, Germany

3. Lei Jin

   Forschungszentrum Jülich · Ernst Ruska Centre · Jülich Aachen Research Alliance

   Affiliation as printed

   Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Juelich GmbH, 52425 Juelich, Germany

   Juelich-Aachen Research Alliance (JARA-FIT), 52425 Juelich, Germany

4. Uwe Breuer

   Forschungszentrum Jülich

   Affiliation as printed

   Central Institute for Engineering, Electronics and Analytics (ZEA-3), Forschungszentrum Juelich GmbH, 52425 Juelich, Germany

5. Regina Dittmann

   Forschungszentrum Jülich · Jülich Aachen Research Alliance

   Affiliation as printed

   Juelich-Aachen Research Alliance (JARA-FIT), 52425 Juelich, Germany

   Peter Gruenberg Institute (PGI-7), Forschungszentrum Juelich GmbH, 52425 Juelich, Germany

6. Rainer M. Waser Aachen Institute for Electronic Materials II (IWE II)

   Forschungszentrum Jülich · Jülich Aachen Research Alliance · RWTH Aachen University

   Affiliation as printed

   Institute for Electronic Materials II (IWE II), RWTH Aachen University, 52056 Aachen, Germany

   Juelich-Aachen Research Alliance (JARA-FIT), 52425 Juelich, Germany

   Peter Gruenberg Institute (PGI-7), Forschungszentrum Juelich GmbH, 52425 Juelich, Germany

7. Olivier Guillon Aachen Institute of Mineral Engineering (GHI)

   Forschungszentrum Jülich · Jülich Aachen Research Alliance · RWTH Aachen University

   Affiliation as printed

   Institute of Energy and Climate Research (IEK-1), Forschungszentrum Juelich GmbH, 52425 Juelich, Germany

   Institute of Mineral Engineering (GHI), RWTH Aachen University, 52062 Aachen, Germany

   Juelich-Aachen Research Alliance (JARA-Energy), 52425 Juelich, Germany

8. Christian Lenser corresponding

   Forschungszentrum Jülich

   Affiliation as printed

   Institute of Energy and Climate Research (IEK-1), Forschungszentrum Juelich GmbH, 52425 Juelich, Germany

9. Felix Gunkel corresponding

   Forschungszentrum Jülich · Jülich Aachen Research Alliance

   Affiliation as printed

   Juelich-Aachen Research Alliance (JARA-FIT), 52425 Juelich, Germany

   Peter Gruenberg Institute (PGI-7), Forschungszentrum Juelich GmbH, 52425 Juelich, Germany