Oxygen membranes and Solid Oxide Fuel Cells (SOFC)
The performance of oxygen membranes and Solid Oxide Fuel Cells (SOFC) relies on the oxygen transport through an electrolyte. A popular electrolyte is yttria stabilized zirconia (YSZ). Using LEIS it has been found that at the operation temperature trace impurities in the YSZ segregate to the surface and block the oxygen diffusion. This impurity segregation was found to be typical for YSZ samples heated in oxygen at temperatures of 700°C or higher.
YSZ after calcination
The main surface constituents are calcium- and hafniumoxide. Since there is no Y or Zr peak, these elements are not present in the outer surface. The strong increase in the background at energies below 2700 eV demonstrates that the 2nd and deeper layers do consist of yttria and zirconia.