The impurity diffusion of Se in polycrystals was investigated by using radio-tracer and serial sectioning techniques, involving 75Se, over a temperature range of 600K. In the type-B Harrison regime,

sD(m3/s) = 6.6 x 10-15exp[-52.8(kJ/mol)/RT]

whereas, in the type-C regime, grain boundaries diffusivities were measured directly and could be described by:

D (m2/s) = 2.6 x 10-7exp[-74.6(kJ/mol)/RT]

T.Surholt, J.M.Mishin, C.Herzig: Solid State Phenomena, 1995, 41, 113-20. See also: Materials Science Forum, 1996, 207-209, 481-4