Sensing behavior of perovskites GdCo1-xCuxO 3 prepared by solution and ultrasonic-assisted aerosol methods

Abstract

Polycrystalline samples of GdCo1-xCuxO3 (x=0, 0.15, 0.3), were prepared by two different routes: solution and ultrasonic-assisted aerosol decomposition. For both procedures, aqueous solutions containing stoichiometric amounts of Gd(NO3) 36H2O, Co(NO3)26H2O and Cu(NO3)22.5H2O were used. In the solution method, the aqueous solutions were heat-dried at 76°C obtaining precursor powders, these were calcined from 80 to 950°C, in air. In the aerosol method, very small droplets were produced by an ultrasonic generator, then a flow of oxygen transported the mist through a tubular furnace, previously heated at 950°C. Solvent evaporation and chemical reaction takes place at that temperature, and the resulting powder was collected by filtration. X-ray powder diffraction was used to identify the formation of target phases. Surface microstructure of powders was analyzed by SEM, and showed that solution method produced sub-micron particles with irregular shape, whereas the aerosol method yield micron-sized hollow spherical particles. In order to determine gas sensitivity vs. temperature, electrical measurements were made in air, O 2 and CO2, from room temperature to 650°C. The results showed a semiconductor behavior and a moderate gas sensitivity for samples prepared by solution method. However, unreliable data were registered for samples made by the aerosol route, caused by short connectivity between particles. © 2005 Materials Research Society.