Chemical diffusion and oxygen exchange of La0.6Sr0.4Co0.6Fe0.4O3−δ

✍ Scribed by J.E. ten Elshof; M.H.R. Lankhorst; H.J.M. Bouwmeester

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 370 KB
• Volume: 99
• Category: Article
• ISSN: 0167-2738
• DOI: 10.1016/s0167-2738(97)00263-4

✦ Synopsis

The transport parameters of La Sr Co Fe O were determined by electrical conductivity relaxation and high 0.6 0.4 0.6 0.4 32d temperature coulometric titration experiments. The experimental response curves were analyzed in the frequency domain. The results obtained by both methods were in good agreement. The chemical diffusion coefficients measured at temperatures 26 25 2 2 1 of 923-1255 K and oxygen partial pressures of 0.03-1 bar O , vary between 10 -5 3 10 cm s . The experimental 2 21 activation energies are in the range 95-117 kJ mol . At oxygen partial pressures below 0.03 bar O the re-equilibration 2 process is completely governed by the rate of oxygen exchange at the interface. The surface exchange coefficients were 24 determined by conductivity relaxation experiments at temperatures of 1000-1285 K and oxygen pressures of 10 -0.1 bar 21 O . The activation energy is about 60-70 kJ mol . The exchange coefficients are almost proportional to the oxygen 2 pressure. Treatment of the surface in a nitric acid solution for several hours increases the surface exchange rates by factors of 3-5.