INVESTIGATION OF GRAIN-BOUNDARY SEGREGATION IN ACCEPTOR AND DONOR-DOPED STRONTIUM-TITANATE

Grain boundary segregation in electronic ceramics is often responsible for dictating the grain boundary properties, which in turn dictate th e macroscopic electronic properties of the material. Consequently, it is important to understand the nature of segregation phenomena in thes e materials. Here we present results from a combination of diverse ana lytical techniques used to investigate the character of grain boundary segregation in acceptor (Fe, Mn) and donor (Nb) doped strontium titan ate. X-ray emission spectroscopy (XES) and Electron energy loss spectr oscopy (EELS) analysis consistently show segregation of both acceptor (Fe, and Mn) and donor (Nb) dopant species to the grain boundaries. Wi thin the spatial resolution of the techniques, the segregation profile s for these dopants are found to be limited to less than 5 nm about th e grain boundaries. Furthermore secondary ion mass spectroscopy shows that the segregation is ubiquitous throughout the samples, and not lim ited to selected grain boundaries.