The O diffusion coefficients of undoped and La-doped BaTiO3 (figure 21) were evaluated by secondary ion mass spectrometry. The La-doped BaTiO3 had markedly lower O diffusion coefficient than the undoped BaTiO3. Regarding the effect of the amount of La doped, the volume diffusion coefficient of O was found to be dependent upon the amount of La doping. The O diffusion behavior of samples synthesized by various cooling processes was also compared. The samples that were very slowly cooled (2C/h from 1250 to 700C) showed markedly low O diffusion coefficient in the low-temperature region. It was found that the difference in cooling rate during the calcination process had significant effect on the O diffusion behavior of La-doped BaTiO3. Regarding the electrical properties of samples, the dielectric properties were strongly influenced by the cooling rate, whereas the direct-current resistivities were not influenced by the cooling rate.

Oxygen Defects Related to Electrical Properties of La-doped BaTiO3. J.Itoh, D.C.Park, N.Ohashi, I.Sakaguchi, I.Yashima, H.Haneda, J.Tanaka: Japanese Journal of Applied Physics - 1, 2002, 41[6A], 3798-803