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@INPROCEEDINGS{Tileli:827177,
author = {Tileli, Vasiliki and Ahmad, Ehsan and Webster, Ross and
Mallia, Giuseppe and Duchamp, Martial and Stoerzinger,
Kelsey and Shao-Horn, Yang and Dunin-Borkowski, Rafal and
Harrison, Nicholas},
title = {2016{D}ecoupling of valence and coordination number
contributions at perovskite surfaces},
address = {Weinheim, Germany},
publisher = {Wiley-VCH Verlag GmbH $\&$ Co. KGaA},
reportid = {FZJ-2017-01375},
pages = {934- 935},
year = {2016},
comment = {European Microscopy Congress 2016: Proceedings},
booktitle = {European Microscopy Congress 2016:
Proceedings},
abstract = {Perovskite oxide nanostructures are on the forefront of
technology due to the wide spectrum of possible applications
pertinent to renewable energy sources, such as
water-splitting, solar cells, fuel cells, batteries, and
catalysis. In particular, the exceptional properties for the
oxygen reduction reaction in catalysis have been detailed
recently in a volcano plot and the results reveal that
orthorhombic, Jahn-Teller distorted LaMnO3 perovskite
nanoparticles are the leading, non-noble metal candidate for
enhanced catalytic activity on the cathode electrode of fuel
cells [1]. Since the functional properties of these
nanoparticles lie on their active surfaces, our approach
involves a detailed structural and chemical evaluation of
the surfaces on the atomic scale to determine what/where the
reaction centres are. Subsequently, the morphology of the
particles can be optimised to maximise the number of these
reaction centres, allowing us to attain the highest possible
performance of perovskite catalysts.From structural
transmission electron microscopy (TEM) data it was
determined that polar facets exist on crystallites, which
lead to assumptions on possible surface
reconstruction/relaxation. However, high resolution TEM
indicated that the atomic terminations of several surfaces
remained defect-free up to the very surface with no visible
reconstruction taking place [2], as shown in Figure 1. Next,
the surface and subsurface of the working perovskite
catalyst was probed by high spatial and temporal resolution
electron energy-loss spectroscopy (EELS) in scanning TEM
mode. The results revealed that the surface shows different
character than the bulk. Tan et al. has previously shown
that different oxidation states of Mn can be probed at
neighbouring sites in the same compound [3] but it was also
theoretically predicted that such a change can be attributed
to coordination number differences as well [4]. Indeed, the
extracted experimental information by EELS for the pristine
LaMnO3 powder was analysed utilising density functional
theory calculations under the optic matrix elements
approximation, as shown for the Mn L3 peak in Figure 2, and
the shift to lower energies of the Mn L3,2 edge was found to
be a convolution of both changes in oxidation state and in
the number of nearest neighbours (coordination).},
month = {Aug},
date = {2016-08-28},
organization = {16th European Microscopy Congress (EMC
2016), Lyon (France), 28 Aug 2016 - 2
Sep 2016},
cin = {PGI-5 / ER-C-1},
cid = {I:(DE-Juel1)PGI-5-20110106 / I:(DE-Juel1)ER-C-1-20170209},
pnm = {143 - Controlling Configuration-Based Phenomena (POF3-143)},
pid = {G:(DE-HGF)POF3-143},
typ = {PUB:(DE-HGF)8 / PUB:(DE-HGF)7},
doi = {10.1002/9783527808465.EMC2016.6949},
url = {https://juser.fz-juelich.de/record/827177},
}