δ-Bi2O3 thin films deposited on dense YSZ substrates by CVD method under atmospheric pressure for intermediate temperature SOFC applications

Thin films of delta-Bi2O3 were grown on a dense Yttria Stabilized Zirconia (YSZ) substrate under atmospheric pressure by means of halide chemical vapour deposition (AP-HCVD) using BiI3 and O-2 as starting materials. X-ray diffraction (XRD) profiles confirm that above 700 degrees C delta-Bi2O3 film with a cubic structure is formed. When the delta-Bi2O3 is deposited at 850 degrees C, the < 111 > direction is preferred. Scanning electron microscopy (SEM) observation revealed that the surface of the film appeared granular and homogeneous with average grain size about 15 mu m. The thermal stability investigation shows that the delta-Bi2O3 films keep its fcc structure up to an annealing temperature of 350 degrees C, above which it transforms into the gamma-Bi2O3 bcc structure. (c) 2005 Elsevier B.V. All rights reserved.