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@ARTICLE{Meyer:31698,
author = {Meyer, R. and Waser, R. and Helmboldt, J. and Borchardt,
G.},
title = {{C}ationic surface segregation in donor-doped {S}r{T}i{O}3
under oxidizing conditions},
journal = {Journal of electroceramics},
volume = {9},
issn = {1385-3449},
address = {Dordrecht [u.a.]},
publisher = {Springer Science + Business Media B.V},
reportid = {PreJuSER-31698},
pages = {101 - 110},
year = {2002},
note = {Record converted from VDB: 12.11.2012},
abstract = {The influence of high temperature oxygen annealing on (100)
oriented donor-doped SrTiO3 single crystals was studied.
Crystalline precipitates were found on the optical scale on
surfaces of lanthanum-doped as well as niobium-doped
specimens with donor concentrations above 0.5 $at.\%.$ The
amount of the secondary phase increases with the doping
level, oxidation temperature and oxidation time. EDX
analyses of the crystallites reveal a SrOx composition.The
formation of the observed secondary phase is discussed by
means of the defect re-equilibration of the cation
sub-lattice. In view of the point defect model for
donor-doped perovskites, n-conducting SrTiO3 changes its
compensation mechanism during an oxidation treatment from
"electronic compensation" (N-D = n) to "self-compensation"
(N-D = 2[V-Sr"]) by forming cation vacancies. Due to the
favored Schottky-type disorder in perovskites, the formation
of strontium vacancies is accompanied by a release of
strontium from the regular lattice. Since the excess
strontium is found to be situated at the surface in form of
SrO-rich precipitates only, we propose the formation of
strontium vacancies via a surface defect reaction and the
chemical diffusion of strontium vacancies from the surface
into the crystal as the most probable re-equilibration
mechanism for the oxidation treatment of single crystals.The
introduced mechanism is in contrast to an established model
which proposes the formation of Ruddlesden-Popper
intergrowth phases SrO.(SrTiO3)(n) in the interior of the
crystal.},
keywords = {J (WoSType)},
cin = {IFF-EKM},
ddc = {620},
cid = {I:(DE-Juel1)VDB35},
pnm = {Kondensierte Materie},
pid = {G:(DE-Juel1)FUEK242},
shelfmark = {Materials Science, Ceramics},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000180947500002},
url = {https://juser.fz-juelich.de/record/31698},
}