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Integrated impedance based hydrocarbon gas sensors with Na-zeolite / Cr2O3 thin-film interfaces : From physical modeling to devices

Title data

Fischerauer, Alice ; Fischerauer, Gerhard ; Hagen, Gunter ; Moos, Ralf:
Integrated impedance based hydrocarbon gas sensors with Na-zeolite / Cr2O3 thin-film interfaces : From physical modeling to devices.
In: Physica Status Solidi A. Vol. 208 (February 2011) Issue 2 . - pp. 404-415.
ISSN 1521-396X
DOI: https://doi.org/10.1002/pssa.201026606

Official URL: Volltext

Project information

Project title:
Project's official titleProject's id
No informationMo 1060/1-1
No informationMo 1060/4-2
No informationFi 956/1-1
No informationFi 956/1-2

Project financing: Bundesministerium für Wirtschaft und Technologie

Abstract in another language

The impedance at temperatures of some hundred degree Celsius of sodium ion conducting zeolites applied on planar interdigital gold electrodes covered with a thin Cr2O3 film changes very sensitively and selectively when exposed to hydrocarbons. In contrast to comparable ammonia sensors, it was found that the sensing effect occurs at the electrodes, namely at the zeolite/Cr2O3 interface. To explain the sensor effect, impedance spectra are calculated with a model that considers the zeolite conductivity, the semiconducting properties of Cr2O3, and the zeolite/Cr2O3 interface characteristics. A differential equation to describe the time-dependent current through zeolite and Cr2O3 is derived. The impedance spectra are then extracted from the complex amplitude of the first harmonic I1 in the Fourier series associated with this periodic current function. The hydrocarbon concentration influences the charge carrier density in the Cr2O3 film, thus leading to the observed impedance changes. The simulated impedance spectra reproduce the important features of the measured spectra quite well.To avoid photolithographic and thin-film processes for manufacturing a prototype sensor, the technology was transferred to the established industrial thick-film hybrid technology. Electrodes and zeolites were screen-printed and the Cr2O3 film was electroplated. Prototype sensors show a good and long-term stable sensitivity toward hydrocarbons. Interfering gases like NO, CO, or H2 do not affect the sensor signal very strongly, but an unexpected pronounced response toward ammonia was observed.

Further data

Item Type: Article in a journal
Refereed: Yes
Keywords: Gas sensors; zeolites; impedance spectra; Cr2O3; interfaces
Institutions of the University: Faculties
Faculties > Faculty of Engineering Science
Faculties > Faculty of Engineering Science > Chair Measurement and Control Technology
Faculties > Faculty of Engineering Science > Chair Measurement and Control Technology > Chair Measurement and Control Technology - Univ.-Prof. Dr.-Ing. Gerhard Fischerauer
Faculties > Faculty of Engineering Science > Chair Functional Materials
Faculties > Faculty of Engineering Science > Chair Functional Materials > Chair Functional Materials - Univ.-Prof. Dr.-Ing. Ralf Moos
Profile Fields
Profile Fields > Advanced Fields
Profile Fields > Advanced Fields > Advanced Materials
Profile Fields > Emerging Fields
Profile Fields > Emerging Fields > Energy Research and Energy Technology
Research Institutions
Research Institutions > Research Centres
Research Institutions > Research Centres > Bayreuth Center for Material Science and Engineering - BayMAT
Result of work at the UBT: Yes
DDC Subjects: 600 Technology, medicine, applied sciences > 620 Engineering
Date Deposited: 19 Jan 2015 10:09
Last Modified: 18 Feb 2016 06:37
URI: https://eref.uni-bayreuth.de/id/eprint/5618