Grain-boundary structures were examined, in 0.1mol%TiO2-excess material, using high-resolution electron microscopy and electron energy-loss spectroscopy. The grain boundaries were mainly faceted, with a {210}-type habit. The faceted boundaries were associated with an extra Ti-O2 bond with the rutile-like structure.

Grain Boundary Structure in TiO2-Excess Barium Titanate. T.Yamamoto, Y.Ikuhara, K.Hayashi, T.Sakuma: Journal of Materials Research, 1998, 13[12], 3449-52