1. Oxygen Isotope Transport Properties of Yttria-Stabilized Zirconia (YSZ) in O2- and H2O-Containing Atmospheres.
- Author
-
Pietrowski, M. J., De Souza, R. A., Fartmann, M., ter Veen, R., and Martin, M.
- Subjects
OXYGEN isotopes ,SINGLE crystals ,YTTRIA stabilized zirconium oxide ,SECONDARY ion mass spectrometry ,SURFACE reactions - Abstract
Oxygen isotope exchange experiments, H
2 18 O/H2 16 O ('wet' anneals) and18 O2 /16 O2 ('dry' anneals), were performed on single crystal samples of yttria-stabilized zirconia (YSZ) at a temperature of T = 1073 K with subsequent determination of the oxygen isotope profiles in the solid by time-of-flight secondary ion mass spectrometry (ToF-SIMS). Such experiments yielded oxygen tracer diffusion coefficients ( D*) and oxygen tracer surface exchange coefficients ( k*), from both the polished (smooth) and unpolished (rough) sides of single crystal samples, as a function of water partial pressure pH2 O and oxygen partial pressure pO2 . Isothermal values of D* were found to depend on neither pO2 nor pH2 O (nor surface roughness). Isothermal values of k*, in contrast, displayed a strong dependence on pO2 or pH2 O; k*wet was, in addition, 2-3 orders of magnitude higher than k*dry . Surprisingly, surface roughness had little effect on k*wet , whereas rough surfaces exhibited much higher k*dry values than smooth surfaces. Data for k*wet obtained as a function of temperature at pH2 O = 18 mbar show a change in activation enthalpy at T ≈ 973 K. The behavior of k* is discussed in terms of surface composition, surface area and surface reaction mechanisms. [ABSTRACT FROM AUTHOR]- Published
- 2013
- Full Text
- View/download PDF