CONICET | Buscador de Institutos y Recursos Humanos

Barium stannate, BaSnO3, is a cubic perovskite-like compound that behaves as a pure n-type semiconductor. Thus, high performance applications, such as sensitive material for exhaust gas sensors, are some of the main reasons for the BaSnO3 demand. Other particular features of this perovskite, and hence the interest in it, are principally related to the easy modification of its electrical properties and its high temperature stability, where the responses of gas-sensitive metal oxides are fast and independent of fluctuations in humidity. In the last years, experimental studies have been carried out, in order to determine its potential usefulness in gas sensors production as tools for detecting toxic and inflammable gases such as CO. For our studies, thick, porous film samples were made by painting onto insulating alumina substrates on which electrodes with an interdigitated shape were deposited by sputtering. After painting, the samples were thermally treated up to 380 °C and exposed to an air atmosphere at 380 °C during 1 hour. The films surface microstructures were characterized using X-ray Diffraction (XRD) and scanning electron microscopy (SEM) and the substrates microstructure was studied using a profilometer. The electrical conduction mechanisms were theoretically modeled considering oxygen in-out diffusion. Finally, we analyzed the film sensor response to oxygen and CO atmospheres at different concentrations. The electrical resistance and capacitance vs. applied bias were also studied. The sensitivity (S) was determined as a function of the temperature in order to find its maximum value.