Experiments were performed for the study of the influence of impurities on the microstructure and hardness of nanocrystalline Ni films. The samples were prepared by electrodeposition using two basic electrolyte solutions (a sulfate-type bath and a Watts-type bath). The effect of saccharin as organic additive on the microstructure, texture and hardness was studied. It was found that the Watts bath without saccharin yielded a larger grain size compared to its sulfatetype counterpart. For both electrolyte solutions, (220) out-of-plane texture was formed in the saccharin-free films. The additive saccharin eliminated the texture and yielded very fine microstructures with high dislocation densities and twin fault probabilities for both solution types. The influence of saccharin on the defect density was higher for the film prepared from the sulfate-type bath. It was revealed that there is a correlation between the defect density and the grain size. When saccharin was added to the Watts bath, the combined effect of nickelchloride and saccharin led to a bimodal grain size distribution. An additional sample was deposited from an electrolyte containing trisodium citrate to investigate the sodium incorporation in the Ni layers. The correlation between the microstructure and the hardness of the films was discussed in detail.

The purpose of the present study was to provide a reliable value for the specific grain-boundary resistivity ρ SGBR of Ni metal. New results are presented on the room-temperature electrical resistivity of nanocrystalline (nc) Ni metal samples produced by electrodeposition with various grain sizes. These resistivity data were compared with previous reports on nc-Ni and all results were analysed according to the procedure of Andrews [Phys. Lett. 19, 558 (1965)] who found that the resistivity increment due to grain boundaries is proportional to the grain-boundary surface area per unit volume which is, on the other hand, inversely proportional to the grain size. It is pointed out that the grain size directly accessible by transmission electron microscopy imaging is the relevant parameter for the evaluation of ρ SGBR whereas the crystallite size deduced from X-ray diffraction line broadening leads to an underestimation of ρ SGBR because coherency-breaking intragrain defects not contributing significantly to the resistivity also cause a line broadening. From the evaluation of the nc-Ni resistivity data at room temperature, we find that 4.45•10 −16 Ω•m 2 < ρ SGBR (Ni) < 6.2•10 −16 Ω•m 2 and our upper bound agrees exactly with the most recent calculated value in the literature.