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@ARTICLE{Pithan:874909,
author = {Pithan, Christian and Katsu, Hayato and Waser, Rainer},
title = {{D}efect chemistry of donor-doped {B}a{T}i{O} 3 with
{B}a{O}-excess for reduction resistant {PTCR} thermistor
applications – redox-behaviour},
journal = {Physical chemistry, chemical physics},
volume = {22},
number = {15},
issn = {1463-9084},
address = {Cambridge},
publisher = {RSC Publ.},
reportid = {FZJ-2020-01697},
pages = {8219-8232},
year = {2020},
abstract = {The electrical conductivity of donor-doped BaTiO3
thermistor ceramics with excessive BaO revealing a
reduction-persistent PTCR effect has been carefully examined
depending on materials’ composition and oxygen partial
pressure at moderate temperatures between 973 and 1273 K.
This thermal regime represents the range which is relevant
for the realization of insulating grain boundaries in these
electrically inhomogeneous ceramic materials through
reoxidation. Based on the experimental results strong
evidence for a general correlation between the PTCR
characteristics, DC-conductivity and the herewith associated
defect chemistry significant to thermistor applications is
presented for the system (Ba, La)mTiO3, where m designates
the BaO-excess (m ≥ 1). Nominal compositions with a
relatively low (Ba + La)/Ti ratio m only show a rather poor
PTCR effect and an overall donor-type response in
conductivity can be observed at all levels of oxygen partial
pressure considered in the present study. With increasing
(Ba + La)/Ti ratio m the nonlinear resistivity jump with
increasing temperature strongly improves and the
acceptor-type behaviour seems to dominate the total
conductivity at partial pressures of oxygen above
approximately 10−6 MPa. This result for compositions with
high BaO-excess can be understood by the local formation of
point defect associates in the grain boundary regions that
consist of both acceptor-type titanium vacancies and
donor-type oxygen vacancies. Their origin is attributed to
the preferential local incorporation of excessive BaO into
the BaTiO3 lattice at the intergranular interfaces.},
cin = {PGI-7 / JARA-FIT},
ddc = {540},
cid = {I:(DE-Juel1)PGI-7-20110106 / $I:(DE-82)080009_20140620$},
pnm = {524 - Controlling Collective States (POF3-524)},
pid = {G:(DE-HGF)POF3-524},
typ = {PUB:(DE-HGF)16},
pubmed = {pmid:32249854},
UT = {WOS:000529178800052},
doi = {10.1039/C9CP06793K},
url = {https://juser.fz-juelich.de/record/874909},
}