Microstructure, oxygen stoichiometry and electrical conductivity of flame-sprayed Sm0.7Sr0.3CoO3-δ

A SSC deposit has been prepared by flame Spraying using Sm0.7Sr0.3CoC3-delta (SSC) powder synthesized by a solid-state reaction. A post-spray annealing treatment of the SSC deposit has been performed. The coating characterization includes: the electrical conductivity of the SSC deposit along the lamellar direction measured by a four-electrode D.C. approach, the microstructures of SSC powders and deposits characterized using X-ray diffraction and scanning electron microscopy, the oxygen stoichiometry ill both the as-sprayed and annealed deposits and starting powder determined by redox titration. The results show that a significant oxygen deficiency (12%) occurs in the sprayed powder particles during high temperature flame spraying, leading to reduction of the electrical conductivity of the as-sprayed SSC deposit. It is found that oxygen call be recovered through post-spray annealing treatment. After annealing at 900 C for 5 h or at 1100 C for 10 h, the electrical conductivity of annealed SSC reaches 433 S cm(-1) or 510 S cm(-1) at 600 degrees C due to a sharp recovery of deficient oxygen and microstructural change. (C) 2009 Elsevier B.V. All rights reserved.