Study of non-stoichiometric BaSrTiFeO3 oxide dedicated to semiconductor gas sensors

8th International Conference on Physics and its Applications

Fasquelle, D.^1 ; Verbrugghe, N.^1 ; Deputier, S.^2

Unité de Dynamique et Structure des Matériaux Moléculaires (UDSMM), Université du Littoral Côte d'Opale, 50 rue F. Buisson, Calais

62228, France^1

Institut des Sciences Chimiques de Rennes(ISCR), UMR 6226 CNRS, Université de Rennes 1, Campus de Beaulieu, Rennes Cedex

35042, France^2

关键词: Cost-effective sensors;    Dielectric constant values;    Instrumentation systems;    Non-stoichiometric composition;    Physical characterization;    Restriction of hazardous Substances;    Semiconductor gas sensors;    Stoichiometric compositions;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/776/1/012038/pdf
DOI  :  10.1088/1742-6596/776/1/012038

来源: IOP

【 摘 要 】

Developing instrumentation systems compatible with the European RoHS directive (restriction of hazardous substances) to monitor our environment is of great interest for our society. Our research therefore aims at developing innovating integrated systems of detection dedicated to the characterization of various environmental exposures. These systems, which integrate new gas sensors containing lead-free oxides, are dedicated to the detection of flammable and toxic gases. We have firstly chosen to study semiconductor gas sensors implemented with lead-free oxides in view to develop RoHS devices. Therefore thick films deposited by spin-coating and screen-printing have been chosen for their robustness, ease to realize and ease to finally obtain cost-effective sensors. As crystalline defects and ionic vacancies are of great interest for gas detection, we have decided to study a non-stoichiometric composition of the BaSrTiFeO3sensible oxide. Nonstoichiometric BaSrTiFeO3lead-free oxide thick films were deposited by screen-printing on polycrystalline AFO3substrates covered by a layer of Ag-Pd acting as bottom electrode. The physical characterizations have revealed a crystalline structure mainly composed of BaTiO3pseudo-cubic phase and Ba4Ti12O27monoclinic phase for the powder, and a porous microstructure for the thick films. When compared to a BSTF thick film with a stoichiometric composition, a notable increase in the BSTF dielectric constant value was observed when taking into account of a similar microstructure and grain size. The loss tangent mean value varies more softly for the non-stoichiometric BaSrTiFeO3films than for the perovskite BSTF film as tanδ decreases from 0.45 to 0.04 when the frequency increases from 100 Hz to 1 MHz.