Electrical properties of the perovskite Y0.9Sr 0.1CoO3-? prepared by a solution method

Single-phase Y0.9Sr0.1CoO3- ? powders were prepared using a solution method based on the dissolution in aqueous media of stoichiometric amounts of yttrium, strontium and cobalt nitrates. Precursor powders were slowly heated from 90 to 950 �C in air. Structural evolution was investigated by X-ray powder diffraction (XRD) as a function of increasing calcination temperature. Differential thermal analysis performed up to 1200 �C was used to identify the temperature of formation for Y0.9Sr0.1CoO3-?, which occurred at ?912 �C. Single-phase polycrystalline powders having the perovskite structure were synthesized at 950 �C, their microstructure and particle size were determined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Thick films of Y0.9Sr 0.1CoO3-? were deposited by the screen printing method on alumina substrates, in order to evaluate their electrical conductivity from room temperature to 700 �C. These measurements were performed in presence of air, oxygen and nitrogen. A semiconductor behavior with possible mixed ionic-electronic conductivity was observed. Sensitivity to nitrogen and oxygen showed a maximum at 579 and 557 �C, respectively. � 2004 Elsevier Ltd. All rights reserved