The diffusion of O near to grain boundaries in this ceramic was studied by using transmission electron microscopic, secondary ion mass spectroscopic, and Auger electron spectroscopic methods. According to the electron microscopic and Auger results, a secondary phase was formed at the grain boundaries. Its composition was estimated to be roughly Bi:Ti:O = 2:2:7; with a small amount of Sr. Additives, such as Bi, Ca and Na, diffused preferentially along grain boundaries. The O grain-boundary diffusion was not as rapid as lattice diffusion in most of the samples. However, only in a Mn-doped sample was a O high-diffusivity path formed at the grain boundary.

K.Ito, S.Shibagaki, H.Haneda, J.Tanaka, S.Shirasaki: Materials Science Forum, 1993, 126-128, 177-80