  The microstructure of electrodeposited Ni films produced without and with
organic additives (saccharin and formic acid) was investigated by X-ray
diffraction (XRD) line profile analysis and cross-sectional transmission
electron microscopy (TEM). Whereas the general effect of these additives on the
microstructure (elimination of columnar growth as well as grain refinement) was
reproduced, the pronounced intention of this study was to compare the results
of various seldom-used high-performance structural characterization methods on
identical electrodeposited specimens in order to reveal fine details of
structural changes qualitatively not very common in this field. In the film
deposited without additives, a columnar structure was observed showing
similarities to the T-zone of structure zone models. Both formic acid and
saccharin additives resulted in equiaxed grains with reduced size, as well as
increased dislocation and twin fault densities in the nanocrystalline films.
Moreover, the structure became homogeneous and free of texture within the total
film thickness due to the additives. Saccharin yielded smaller grain size and
larger defect density than formic acid. A detailed analysis of the grain size
and twin boundary spacing distributions was carried out with the complementary
application of TEM and XRD, by carefully distinguishing between the TEM and XRD
grain sizes.
