EFFECT OF THERMAL TREATMENT ON THE 4f-HOPPING CONDUCTIVITY OF CeO2 EXPOSED TO CO(g) ATMOSPHERE

In this work, the effect of the thermal treatment of CeO2 on the film response against CO is analyzed. The powders characterization was performed using the techniques of X-Rays Diffraction, Raman Spectroscopy, UV-Visible and Scanning Electron Microscopy. A fluorite-type crystalline structure was observed in both samples, with the one calcined at 900°C presenting a higher degree of crystallinity as well as a defined morphology formed by the set of (100), (110) and (111) surfaces. The band-gap energy value obtained was 3.35 and 3.37 eV, for the 600 and 900°C samples, respectively. The two-point probe technique was used for the electrical resistance measurements as a function of temperature in gaseous atmospheres such as dry air (760 mmHg), vacuum (10-3 mmHg) and carbon monoxide (CO, 100 mmHg). Finally, the values of the activation energy and pre-factors A in air, vacuum and CO were calculated for correlating the electrical measurements with the sample morphologies.