Abstract
The nucleation, growth process and structure of gold film electrodeposited on iron from aqueous solution of HAuCl4 containing K2CO3 were examined by electron microscope. The results obtained were as follows: (1) The density of muclei formed at the initial stage of electrodeposition was about 2×1011cm-2. Among these nuclei, there were present pentagonal and hexagonal particles, which seemed to be multiply twinned particles. However, the ratio of these twinned particles to the total nuclei was very small. (2) The pentagonal and hexagonal particles grew up to about 400Å in size. (3) The growth process was distiuguished into the following four stages: (a) Formation of nuclei. (b) Formation of insular crystals resulting from coalescence and growth of nuclei. (c) Formation of network structure resulting from two dimensional growths of insular crystals. (d) Accomplishment of plate crystals resulting from progressing of deposition in the non-covered area. (4) The normal micro-twins were formed in the gold plate crystals during the growth process. (5) The following coherency was found between the iron substrate and gold plate crystals: (001) Fe|| (001) Au and <110> Fe|| <100> Au. (6) The addition of K2CO3 to aqueous solution of HAuCl4 had an effect on the two dimensional growth of gold film; The effect increased the covering rate of substrate with gold film.
