Effects of aromatic carbonyl compounds on the surface morphology and crystal orientation of electrodeposited tin from acid stannous sulfate solutions

The effects of three kinds of aromatic carbonyl compounds [cinnamaldehyde(CA), benzalacetone(BA), 2-acetonaphthone(AN)] and N,N-bis(tetraoxyethylene)octadecylamine(TOOA) on the surface morphology as well as crystal orientation of electrodeposited tin from acid stannous sulfate solutions have been studied by means of electrochemical methods, scanning electron microscopic observation and measurements of X-ray diffraction patterns. The inhibitory effects of the reduction of tin(II) ion became stronger in the order BA, CA and AN in the case of oxidant, and in the order CA, AN and BA in the case of reductant. The differences in the inhibitory effects between the oxidant and reductant became greater in the order of AN, CA and BA. Block-like crystals were observed on the whole surface by adding TOOA. Plate-like, needle-like or dendritic crystals were observed but compact electrodeposits could not be obtained by adding carbonyl compounds alone. On the other hand, compact and smooth electrodesposits of tin which had a preferred orientation with the (100) plane parallel to the surface were obtained from acid stannous sulfate solutions containing TOOA and BA.