The diffusion characteristics of Ni ions were evaluated in non-doped, Ho-doped polycrystalline and single-crystal barium titanate perovskite using secondary ion mass spectrometry. The bulk diffusion coefficients of Ni at 1100 to 1400C were described by:

non-doped:     D(cm2/s) = 1.4 x 10-6 exp[-241.9(kJ/mol)/RT]

Ho-doped:     D(cm2/s) = 4.4 x 10 -6 exp[-227.7(kJ/mol)/RT]

single-crystal:     D(cm2/s) = 6.7 x 10 exp[-437.2(kJ/mol)/RT]

J.I.Itoh, I.Yashima, N.Ohashi, I.Sakaguchi, H.Haneda, J.Tanaka: Journal of the Ceramic Society of Japan, 2001, 109[1275], 955-9