| Abstract Scope |
While the bulk defect chemistry of nominally undoped and doped ceria is relatively well-known, the interfacial defect chemistry remains less clear. There is general consensus that exposed surface and grain boundaries of ceria are more reduced that the bulk, but beyond that, the details are murky, particularly because charge neutrality can be violated in the near proximity of surfaces. Furthermore, dopant and impurity segregation to interfaces can further complicate interfacial behavior and distinguish these regions from the bulk. Moreover, while bulk defect chemistry can be readily assessed by in situ methods (impedance spectroscopy and thermogravimetric analysis), such methods are generally unsuited to interfacial studies. Accordingly, interfaces in ceria have been most commonly been studied by electron spectroscopy methods, but these are rarely performed in situ, at the temperatures and gas environments relevant to device applications. Here I present our studies using a range of techniques to study grain boundaries and exposed surfaces of ceria, focusing on X-ray absorption spectroscopy, a technique that is compatible with device relevant conditions. |