From the sintered cylindrical compacts, 1-mm-thick diffusion samples
were cut with surface dimensions of 5 × 5 mm2. This eliminates
the influence of cross diffusion from the 1-mm-thick sides to the diffusion
profile resulting from diffusion through the 5 × 5 mm2 sides of the
sample. Finally, one of the sample surfaces was mechanically polished with diamond paste in several grinding and polishing steps, with a
final finish using a 0.25-micron lapping solution. These one side
polished samples have been used for the self-diffusion experiments.