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@PHDTHESIS{Siemons:52336,
author = {Siemons, Maike},
othercontributors = {Simon, Ulrich},
title = {{H}igh throughput methods for synthesis and impedance
characterisation of {ABO}3 gas sensing materials},
address = {Aachen},
publisher = {Publikationsserver der RWTH Aachen University},
reportid = {RWTH-CONV-114568},
pages = {201 S. : Ill., graph. Darst.},
year = {2007},
note = {Aachen, Techn. Hochsch., Diss., 2006},
abstract = {This PhD thesis deals with the preparation and
characterisation of resistive thick-film gas sensors by use
of high throughput impedance spectroscopy. Since the 1960s
semiconducting resistive gas sensors are used in a wide
range of applications. However, commercial systems show
disadavantages which might be overcome by the use of new
materials. The sensitivity and selectivity of new sensing
materials cannot be predicted resulting from the complex
interplay of different parameters. In sensor research
materials are typically discovered by a “one at a time”
strategy that is both time consuming and costly. A possible
way to overcome these problems is the use of high throughput
research which enables the screening of a multitude of
different materials in short time. The polyol method enabled
the preparation of a wide range of different ABO3 compounds.
The fast and simple reaction method allowed mixing on the
molecular level and bulk doping of the materials during the
preparation. Nanoscaled compounds that crystallised after
temperature treatment were achieved. The prepared ABO3
materials offered various properties and possibilities for
gas sensing materials, especially for high temperature use.
The prepared materials were used to fabricate active layers
on electrode structures to form gas sensors. Substrate
plates of diverse metal-doped oxides were rapidly
synthesised and screened with the high throughput impedance
spectroscopy setup. 64 different materials could be screened
on one multi electrode substrate. The measurements were
performed between 200 and 500°C and the test gases were
hydrogen, carbon monoxide, nitrogen oxides, ethanol, and
propylene in synthetic air. Two different material systems,
CoTiO3 and LnMO3 (Ln=lanthanide, M=Cr, Fe), were presented
in detail. All prepared materials showed typical p-type
semiconduncting behaviour. Incorporation of various volume
dopants into CoTiO3 changed the resistance and improved the
sensing properties of the base material. Lanthanum doping
was found to be most effective. By introducing to CoTiO3:La
a number of surface and solid surface dopants in different
concentrations, the sensitivity was influenced. Secondly,
the preparation and characterisation of 25 lanthanide
orthochromites LnCrO3 and orthoferrites LnFeO3 was
described. They all showed hydrocarbon and NO2 sensitivity.
One of the outstanding materials, SmFeO3, was investigated
further towards volume and surface doping influences. From
the measurements on LnMO3 materials, a trend in sensing
performance as a function of composition was found. The
sensitivity of these materials was inversely connected to
the binding energy of the compounds. Changes of the M-site
cation had more influence on the sensitivity than changes in
the Ln-site. The materials shown here have high potential
for gas sensing applications. With the use of high
throughput impedance spectroscopy, a great number of
different compounds were screened in a short amount of time.
Only the great number of measuring data achieved under
comparable conditions allowed to find structure-property
relations.},
cin = {150000 / 151310},
ddc = {540},
cid = {$I:(DE-82)150000_20140620$ / $I:(DE-82)151310_20140620$},
typ = {PUB:(DE-HGF)11},
urn = {urn:nbn:de:hbz:82-opus-17746},
url = {https://publications.rwth-aachen.de/record/52336},
}
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