Defects in film samples of these materials were compared by means of X-ray photo-emission spectroscopic measurements. In the case of the tantalate film, it was found that the O ions in the metal-O octahedra were much more stable than those in the B2O2 layers. On the other hand, in the titanate films the O vacancies could be introduced into both Ti-O octahedra and B2O2 layers.

Differences in Nature of Defects between SrBi2Ta2O9 and Bi4Ti3O12. B.H.Park, S.J.Hyun, S.D.Bu, T.W.Noh, J.Lee, H.D.Kim, T.H.Kim, W.Jo: Applied Physics Letters, 1999, 74[13], 1907-9