| AVS 54th International Symposium | |
| Thin Film | Thursday Sessions |
| Session TF1-ThA |
| Session: | Photovoltaics, Fuel Cells, and Alternative Energy Materials and Applications |
| Presenter: | M. Finsterbusch, Montana State University and Technische Universitaet Ilmenau, Germany |
| Authors: | M. Finsterbusch, Montana State University and Technische Universitaet Ilmenau, Germany H. Chen, Montana State University W. Priyantha, Montana State University V. Shutthanandan, Pacific Northwest National Laboratory R.J. Smith, Montana State University J.A. Schaefer, Technische Universitaet Ilmenau, Germany |
| Correspondent: | Click to Email |
Yttria stabilized zirconia (YSZ) is one of the most common solid ionic conductors considered for the electrolyte in solid oxide fuel cells operating at temperatures near 800oC. The addition of yttria into zirconia not only stabilizes the cubic fluorite phase of zirconia over a wide temperature range, but also introduces oxygen vacancies due to the smaller valency of Y3+ vs. Zr4+. High oxygen ionic conductivity associated with vacancy hopping is seen in YSZ for yttria doping levels around 10%. Numerous studies have been carried out to understand oxygen transport and surface exchange kinetics in single crystal YSZ.1-3However, for polycrystalline YSZ the description of diffusion processes is more complex due to the presence of interfaces and grain boundaries that act as preferential sites for variation in composition and chemical state of the atomic species with respect to the bulk. In this study 18O tracer depth profiles were obtained using 18O(p,α)15N nuclear reaction analysis for both YSZ single crystals and sintered polycrystalline pellets. Samples were cleaned and pre annealed in a tube furnace for 8 hours at 800oC in air. Afterwards they were exposed for various times at a pressure of 10 Torr of 99% pure 18O at various temperatures up to 900oC. By contrasting the differences of 18O transport for the two structures, the influence of grain boundaries on oxygen transport and exchange kinetics were extracted.
*HiTEC is funded by DOE as a subcontract from Battelle Memorial Institute and Pacific Northwest National Laboratory under Award No.DE-AC06-76RL01830.
1 R. Roewer, G. Knoener, K. Reimann, H.E. Schaefer, U. Soedervall; phys. stat. sol. (b) 239, No. 2, R1-R3 (2003)/DOI 10.1002/pssb.200309011
2 N.I. Joos, P.A.W. van der Heide, J.R. Liu, R. Christoffersen, W.K. Chu, C.A. Mims; Mat. res. Soc. Symp. Proc. Vol. 548, Page 605-610
3 P.S. Manning, J.D. Sirman, R.A. De Souza, J.A. Kilner; Solid State Ionic 100 (1997) 1-10.