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@ARTICLE{Szot:844596,
author = {Szot, K. and Rodenbücher, Christian and Bihlmayer, Gustav
and Speier, Wolfgang and Ishikawa, Ryo and Shibata, Naoya
and Ikuhara, Yuichi},
title = {{I}nfluence of {D}islocations in {T}ransition {M}etal
{O}xides on {S}elected {P}hysical and {C}hemical
{P}roperties},
journal = {Crystals},
volume = {8},
number = {6},
issn = {2073-4352},
address = {Basel},
publisher = {MDPI},
reportid = {FZJ-2018-02000},
pages = {241 -},
year = {2018},
note = {enthält Publikationsgebühren (Bildrechte)},
abstract = {Studies on dislocations in prototypic binary and ternary
oxides (here TiO2 and SrTiO3) using modern TEM and scanning
probe microscopy (SPM) techniques, combined with classical
etch pits methods, are reviewed. Our review focuses on the
important role of dislocations in the insulator-to-metal
transition and for redox processes, which can be
preferentially induced along dislocations using chemical and
electrical gradients. It is surprising that, independently
of the growth techniques, the density of dislocations in the
surface layers of both prototypical oxides is high
(109/cm$^2$ for epipolished surfaces and up to 1012/cm2 for
the rough surface). The TEM and locally-conducting atomic
force microscopy (LCAFM) measurements show that the
dislocations create a network with the character of a
hierarchical tree. The distribution of the dislocations in
the plane of the surface is, in principle, inhomogeneous,
namely a strong tendency for the bundling and creation of
arrays or bands in the crystallographic <100> and <110>
directions can be observed. The analysis of the core of
dislocations using scanning transmission electron microscopy
(STEM) techniques (such as EDX with atomic resolution,
electron-energy loss spectroscopy (EELS)) shows
unequivocally that the core of dislocations possesses a
different crystallographic structure, electronic structure
and chemical composition relative to the matrix. Because the
Burgers vector of dislocations is per se invariant, the
network of dislocations (with additional d$^1$ electrons)
causes an electrical short-circuit of the matrix. This
behavior is confirmed by LCAFM measurements for the
stoichiometric crystals, moreover a similar dominant role of
dislocations in channeling of the current after thermal
reduction of the crystals or during resistive switching can
be observed. In our opinion, the easy transformation of the
chemical composition of the surface layers of both model
oxides should be associated with the high concentration of
extended defects in this region. Another important insight
for the analysis of the physical properties in real oxide
crystals (matrix + dislocations) comes from the studies of
the nucleation of dislocations via in situ STEM indentation,
namely that the dislocations can be simply nucleated under
mechanical stimulus and can be easily moved at room
temperature.},
cin = {PGI-7 / JARA-FIT / PGI-1 / IAS-1},
ddc = {540},
cid = {I:(DE-Juel1)PGI-7-20110106 / $I:(DE-82)080009_20140620$ /
I:(DE-Juel1)PGI-1-20110106 / I:(DE-Juel1)IAS-1-20090406},
pnm = {521 - Controlling Electron Charge-Based Phenomena
(POF3-521)},
pid = {G:(DE-HGF)POF3-521},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000436129400010},
doi = {10.3390/cryst8060241},
url = {https://juser.fz-juelich.de/record/844596},
}