The grain-boundary diffusivity of Sr in La0.9Ca0.13CrO3 was determined by means of secondary-ion mass spectrometry; using depth-profiling from the surface or line-scanning of fracture surfaces. Depth profiles which were sputtered using an O2+ primary ion beam gave 2 slopes for the Sr concentration profile. These corresponded to bulk and grain-boundary diffusion. The depth profiles were fitted to an appropriate equation that furnished bulk and grain-boundary diffusion coefficients of 6.5 x 10-20 1.6 x 10-15m2/s, respectively, at 1273K. The line-scanning measurements permitted the successful determination of Sr concentration profiles around the grain boundary. However, the grain-boundary diffusivity which was deduced was equal to 6.0 x 10-13m2/s. This was a factor of 100 greater than that which was obtained using the depth-profiling method.

T.Horita, N.Sakai, T.Kawada, H.Yokokawa, M.Dokiya: Journal of the American Ceramic Society, 1998, 81[2], 315-20