Electron-beam damage and point defects near grain boundaries in cerium oxide

Cerium oxide is a technologically important ceramic with applications in catalysis and potentially as an electrolyte for solid-oxide fuel cells (SOFCs). The technological interest is largely due to the behavior of oxygen vacancies in this material. Grain boundaries play an important role in oxygen vacancy diffusion and, although not completely understood, the influence of grain boundaries has been attributed to both a space-charge effect and the segregation of impurities. In this paper, results from spatially resolved electron-energy-loss spectroscopy (EELS) near grain boundaries in doped CeO2 in a transmission electron microscope (TEM) are reported. The data are interpreted as the result of beam damage that varies as the electron beam is scanned across grain boundaries and suggest a spatially varying concentration of oxygen vacancies near the grain boundaries.