Chemically induced grain-boundary

Brechet, Y. J. M. and Purdy, G. R., A phenomenological description for chemically induced grain boundary migration, Acta MetalL, 37, 2253 59, 1989. 

Lee, H.-Y., and Kang, S.-J. L., Chemically induced grain boundary migration and recrystallization in AI2O3, Acta MetalL Mater., 30, 1307-12, 1990. 

The distribution of these impurities or minor alloy constituents near lattice discontinuities is known to affect the chemical and mechanical properties of the contaminated materials for example the presence of sulfur on a metal surface can promote ) or retard - o) corrosion, modify the surface energy ) or cause considerable increase in the surface self-diffusion coefficient ). Sulfur accumulation along grain boundaries may induce intergranular weakness and render otherwise ductile materials brittle ), either by formation of precipitates " ) or by enhancement of hydrogen adsorption >227)... 

This is the ciystal layer in the vicinity of the grain boundary containing segregation-induced gradients in crystal properties, such as chemical corrrposition and electrical poterrtial. Essentially, its meaning is the same as that in (8) with respect to the grain boundary. 

It was stressed above that the properties of doped CMR manganites cannot be in full measure understood without accounting for the effects induced by various kinds of imperfections (grain boundaries, chemical inhomogeneities, strained regions, etc.). It is this topic that has been under intensive investigation in a number of recent papers. 

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