The grain-boundary structure was examined using high-resolution transmission electron microscopy and electron energy loss spectroscopy. The material was doped with a small amount of cations having a particular tendency to bond chemically. It was found that the grain-boundary structure was sensitive to a small excess of Ti-site dopant. The boundaries were facetted, with {210} habits and an ordered structure. The high-resolution transmission electron microscopic and electron energy loss spectroscopic examinations, combined with molecular orbital calculations, clearly revealed that the TiO6 octahedral linkage changed from corner-sharing, in the grain interior, to edge-sharing at the grain boundary.

Grain Boundary Structure in BaTiO3 with a Small Excess of Ti-Site Dopant. T.Yamamoto, Y.Ikuhara, K.Hayashi, T.Sakuma: Materials Science Forum, 1999, 294-296, 247-50