Codeposition of copper and tin from acid sulphate solutions containing polyether sintanol DS-10 and micromolar amounts of halides

Abstract

Cu(II) and Sn(II) reduction in acid sulphate solutions containing polyether laprol DS-10 was investigated using voltammetric XPS and XRD techniques. Bright yellow bronze coatings can be deposited at potentials ( E) that are positive than equilibrium potential ( E eq Sn ) of Sn|Sn 2+ electrode. Here, Sn(II) reduction might be treated as underpotential deposition (UPD) of tin on foreign (copper) substrate. Further incorporation of tin into integral Cu–Sn crystallic lattice yields the mixture of pure copper, α-CuSn phase and intermediate hexagonal hcp phase. The formation of free tin phase occurs at E < E eq Sn . This gives rise for strong inhibitive adsorption of sintanol that manifests itself in the development of deep voltammetric minimum. Addition of halides results in the shift of codeposition potential to more negative values and in the increase of copper content in the coatings deposited in the UPD region. The action of halides intensifies in the sequence Cl − < Br − < I −. If iodide concentration exceeds 2–3 μM, deposition of yellow bronze becomes impossible.