Fig. 3: Interfacial valence changes seen by STEM/EELS.
From: Colossal oxygen vacancy formation at a fluorite-bixbyite interface
a Atomic-resolution EELS map for the Ce-M4,5 edges from a local area in a CeO2–Y2O3 nanobristle, revealing an atomically abrupt (111) interface. The scale bar corresponds to 1 nm. b Ce-M4,5 EELS spectra averaged along the (111)Ce atom planes. The dashed lines indicate the chemical shift of the Ce-M5 and Ce-M4 edges at the interface between CeO2 and Y2O3 as indicated by the EELS spectra in red. The latter were taken from the two interfacial CeO2 layers interleaved by a Y2O3 layer, indicating the presence of reduced CeO2 layers (~2 u.c. thick). c Average Ce valence states in the (111)Ce atom planes indicated in b, revealing the valence change in interfacial CeO2 layers.
