The structure of yttria-stabilised zirconia: a combined medium energy photoemission and ab-initio investigation
Australian Institute of Physics
Cubic zirconia-based materials are candidates for use in the nuclear fuel cycle. There are three phases of ZrO2, a room temperature monoclinic phase and higher temperature tetragonal and cubic phases. The cubic phase of zirconia, in comparison to the other phases, exhibits a very low thermal conductivity, allowing the material to be potentially used in high temperature fission and fusion environments. Interestingly, the cubic-phase may be stabilised at room temperature through the addition of small quantities of other oxides for example, Y2O3, CaO and Ce2O3. Recent ab initio calculations for yttria-stablised zirconia (YSZ) predict the atomic geometry for various oxygen-vacancy containing structures . In particular, a set of “rules” is used to establish a structure for 6.25 Mol % [1,2]. This model is extended to a yttria content of 9.375 Mol % and compared with a sample of 9.5 Mol % yttria. Using this model, core-level shifts are estimated as changes in binding energy obtained from density-functional theory (DFT) calculations, due to the different chemical environments. The partial density-of-states of Y atoms differ depending upon whether there are oxygen vacancies at nearest-neighbour sites to the Zr atoms. Experimentally, a number of different core-levels and Auger-lines are acquired across the L-edges of Zr and Y. By measuring through the Y Ledge resonance, three distinct Zr environments and three distinct oxygen environments are observed in photoelectron peaks. The area under each peak is plotted against photon energy.
Yttrium, Zirconium compounds, Ambient temperature, Nuclear fuels, Thermal conductivity, Temperature range 0400-1000 K, Fission, Oxygen, Vacancies
Cousland, G., Wong, L., Tayebjee, M., Yu, D., Triani, G., Stampfl, A. P. J., Ciu, X., Stampfl, C. M., & Smith, A. (2011). The structure of yttria-stabilised zirconia: a combined medium energy photoemission and ab-initio investigation. Paper presented to the Australian and New Zealand Institutes of Physics 35th Annual Condensed Matter and Materials Meeting Charles Sturt University, Wagga Wagga, NSW 2nd - 4th February, 2011. Retrieved from: https://physics.org.au/wp-content/uploads/cmm/2011/