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Grazing-incidence electron diffraction at 50â 60 kV shows the surface structure of smooth electropolished Cu (110) faces and of the epitaxial Ni deposits on them from the bath: Ni(SO3· NH2)2· 4H2O 350 g/l., NiCl2· 6H2O 5g/l., H3BO3 35 g/l.The Ni deposits were all f.c.c. The effects of c.d. (up to 600 mA/cm<sup>2</sup>), thickness (100â 60 000 à ), temperature (50 and 20°C), and vigorous stirring, are shown in detail. The effects of codeposition of Ni(OH)2 at high c.d. are also shown.Special points of interest are: (1) at 50°C although {111} twinning of the â parallelâ epitaxial Ni was strong near the interface (100â 200 à Ni deposits) at up to â ¼150 mA/cm<sup>2</sup>, it was weaker at 200 and absent at 300â 600 mA/cm<sup>2</sup>(at least up to thousands of à thickness), and this is similar to our results for Ni on (100) and (111) Cu; (2) at up to â ¼150 mA/cm<sup>2</sup> at 50°C with unstirred bath the strongly twinned Ni at up to 1000 à thickness showed no â directed disorientationâ though accompanied by an extremely small trace of widely disoriented (random?) Ni, possibly associated with the epitaxial misfit and contacting crystal nuclei; (3) at 10 000 à or more, at up to â ¼150 mA/cm<sup>2</sup> at 50°C with unstirred bath, additional weak arcs showed a small amount of {100} Ni, and at 30 000â 60 000 à these arcs became strong and showed a {100} Ni orientation but limited to azimuths associated with those of the {111} twins of the â parallelâ Ni, arising from the twins by a â directed disorientationâ (a range of rotation round the horizontal [11.macr;0] Ni direction, presumably due to contacts between the twins, as they grow, with misfit stresses and strains at their interface), followed by cube face development leading to preferred growth of crystals in {100} orientation. |
