title: Testing the Chemical/Structural Stability of Proton Conducting Perovskite Ceramic Membranes by in Situ/ex Situ Autoclave Raman Microscopy.
abstract: Ceramics, which exhibit high proton conductivity at moderate temperatures, are studied as electrolyte membranes or electrode components of fuel cells, electrolysers or CO2 converters. In severe operating conditions (high gas pressure/high temperature), the chemical activity towards potentially reactive atmospheres (water, CO2, etc.) is enhanced. This can lead to mechanical, chemical, and structural instability of the membranes and premature efficiency loss. Since the lifetime duration of a device determines its economical interest, stability/aging tests are essential. Consequently, we have developed autoclaves equipped with a sapphire window, allowing in situ Raman study in the 25-620 °C temperature region under 1-50 bar of water vapor/gas pressure, both with and without the application of an electric field. Taking examples of four widely investigated perovskites (BaZr0.9Yb0.1O3-δ, SrZr0.9Yb0.1O3-δ, BaZr0.25In0.75O3-δ, BaCe0.5Zr0.3Y0.16Zn0.04O3-δ), we demonstrate the high potential of our unique set-up to discriminate between good/stable and instable electrolytes as well as the ability to detect and monitor in situ: (i) the sample surface reaction with surrounding atmospheres and the formation of crystalline or amorphous secondary phases (carbonates, hydroxides, hydrates, etc.); and (ii) the structural modifications as a function of operating conditions. The results of these studies allow us to compare quantitatively the chemical stability versus water (corrosion rate from ~150 µm/day to less than 0.25 µm/day under 200-500 °C/15-80 bar PH2O) and to go further in comprehension of the aging mechanism of the membrane.
authors: Laboratory of Dynamics, Interactions and Reactivity (LADIR), UMR7075 CNRS, Université Pierre et Marie Curie, 4 Pl. Jussieu, Paris 75005, France. aneta.slodczyk@upmc.fr.
authors: Aneta
authors: A
authors: Slodczyk
authors: Laboratory of Dynamics, Interactions and Reactivity (LADIR), UMR7075 CNRS, Université Pierre et Marie Curie, 4 Pl. Jussieu, Paris 75005, France. missoum83@yahoo.fr.
authors: Oumaya
authors: O
authors: Zaafrani
authors: Department of Materials, Imperial College London, London SW7 2AZ, UK. m.sharp09@imperial.ac.uk.
authors: Matthew D
authors: MD
authors: Sharp
authors: Department of Materials, Imperial College London, London SW7 2AZ, UK. j.kilner@imperial.ac.uk.
authors: John A
authors: JA
authors: Kilner
authors: Department of Physics, Northern Illinois University, DeKalb, IL 60115, USA. dabrowski@anl.gov.
authors: Bogdan
authors: B
authors: Dabrowski
authors: AREVA NP, Université Montpellier 2, Montpellier 34095, France. olivier.lacroix@areva.com.
authors: Olivier
authors: O
authors: Lacroix
authors: Laboratory of Dynamics, Interactions and Reactivity (LADIR), UMR7075 CNRS, Université Pierre et Marie Curie, 4 Pl. Jussieu, Paris 75005, France. philippe.colomban@upmc.fr.
authors: Philippe
authors: P
authors: Colomban