Elaboration and characterization of tin oxide-lanthanum oxide mixed layersprepared by the electrostatic spray pyrolysis technique

Lanthanum oxide-tin oxide mixed layer was found to show promising sensing p roperties to CO2 in the air. In this paper, we describe the characterizatio n of such layers fabricated by the electrostatic spray pyrolysis technique. Analysis by scanning electron microscopy (SEM) and atomic force microscopy (AFM) show a structure of grain aggregates, while energy dispersion analys is reveal that the original and final compositions are very close with an u niformly distribution in the layer. X-ray diffraction gives the nature of t he deposited oxide, which is LaOCl and SnO2. Electrical characterization ve rsus temperature and concentration reveal a sensitivity peak for the 2% lan thanum. oxide mixed layer at about 425 degreesC. A variable frequency (13 M Hz-500 Hz) ac voltage was applied to all the sensor structures to perform. the complex impedance spectrum measurements, at a temperature range 350-550 degreesC, and a CO, concentration range 400-2000 ppm in synthetic air. For all these measurements, we obtain the same equivalent circuit, which fits very well the experimental data, and allows us to propose a conduction mode l. (C) 2001 Published by Elsevier Science B.V.