Thermo-Chemical Expansion of SOFC Materials

The thermo-chemical expansion of Solid Oxide Fuel Cell (SOFC) component materials exposed to different partial pressures of oxygen (PO2) was studied and a model developed that fits the resulting data. Thermo-chemical expansion is made up of two parts, the expansion due to temperature and the expansion due to changes of point defect population as a function of ambient PO2 . The materials of interest in this study were 10mol% gadolinium doped ceria (GDC), undoped ceria, 8mol% yttria stabilized zirconia (YSZ), and 50vol% 8mol% yttria stabilized zirconia and 50vol% nickel (II) oxide composite (YSZ/NiO). The thermo-chemical expansion data were compared to a model that accounts for both expansion due to temperature and creation of oxygen vacancies in the lattice. The parameters of the model were determined from values in the literature. The experimental data validated the model.