TY  - JOUR
AU  - Thalinger, Ramona
AU  - Gocyla, Martin
AU  - Heggen, Marc
AU  - Klötzer, Bernhard
AU  - Penner, Simon
TI  - Exsolution of Fe and SrO Nanorods and Nanoparticles from Lanthanum Strontium Ferrite La $_{0.6}$ Sr $_{0.4}$ FeO $_{3−δ}$ Materials by Hydrogen Reduction
JO  - The journal of physical chemistry  / C
VL  - 119
IS  - 38
SN  - 1932-7455
CY  - Washington, DC
PB  - Soc.
M1  - FZJ-2015-07729
SP  - 22050 - 22056
PY  - 2015
AB  - Formation of uniform Fe and SrO rods as well as nanoparticles following controlled reduction of La0.6Sr0.4FeO3−δ (LSF) and Ni-LSF samples in dry and moist hydrogen is studied by aberration-corrected electron microscopy. Metallic Fe and SrO precipitate from the perovskite lattice as rods of several tenths of nm and thicknesses up to 20 nm. Based on a model of Fe whisker growth following reduction of pure iron oxides, Fe rod exsolution from LSF proceeds via rate-limiting lattice oxygen removal. This favors the formation of single iron metal nuclei at the perovskite surface, subsequently growing as isolated rods. The latter is only possible upon efficient removal of reduction-induced water and, subsequently, reduction of Fe +III/+IV to Fe(0). If water remains in the system, no reduction or rod formation occurs. In contrast, formation of SrO rods following reduction in dry hydrogen is a catalytic process aided by Ni particles. It bears significant resemblance to surface diffusion-controlled carbon whisker growth on Ni, leading to similar extrusion rods and filaments. In addition to SrO rod growth, the exsolution of Fe nanoparticles and, subsequently, Ni–Fe alloy particles is observed. The latter have also been observed under static hydrogen reduction. Under strict control of the experimental parameters, the presented data therefore open an attractive chemically driven pathway to metal nanoarchitectures beyond the formation of “simple” nanoparticles.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000361921600033
DO  - DOI:10.1021/acs.jpcc.5b06014
UR  - https://juser.fz-juelich.de/record/279851
ER  -