Powders of BaSnO3 were synthesized to obtain gas sensor thick films (using the screen printing technique) for the detection of O2 and CO. Impedance spectroscopy was used at different atmospheres and temperatures. In the presence of O2, the films showed a maximum value of sensitivity at 300 °C, with the powders formed by Pechini presenting greater reproducibility and sensitivity (with an order of magnitude greater than that for the powders formed by precipitation). Results showed that the films formed with powders obtained using the Pechini method presented a better response to CO, with a maximum sensitivity at 450 °C. In addition, in the presence of CO and for T > 250 °C, these films showed an anomalous behavior regarding their sensitivity as a function of time when platinum electrodes were used: a great increase in the electrical resistance value for exposure times greater than 10 min.

Zn7Sb2O12 is known to adopt an inverse spinel crystal structure, in which Zn2+ occupies the eight tetrahedral positions and Sb5+ and Zn2+ randomly occupy the 16 octahedral positions. Samples of Zn7−xNixSb2O12 (x=0, 1, 2, 3, and 4) were synthesized using a modified polymeric precursor method, known as the Pechini method. The crystal structure of the powders was characterized by Rietveld refinement with X-ray diffraction data. The results show that for x=0, 1, and 2 Ni substitutes for Zn2+ in the octahedral sites, and that for x=3 and 4 it is assumed that Ni2+ replaces Zn2+ ions in both the octahedral and tetrahedral positions. It is also observed for x=3 and 4 the formation of two spinel phases.