Characterization of the anodic growth and dissolution of antimony oxide films

Characterization of growth of anodic antimony oxide films by ellipsometry and XPS

“…Optical measurements were carried out at a wavelength of 546.1 nm using a Rudolph research rotating-analyzer automatic ellipsometer (vertical type, 2000 FT model). The experimental setup has been previously described [11]. The optical properties of an isotropic single layer are given by its complex refractive index, n = n À ki, where n stands for the refractive index and k for the extinction coefficient [22,23].…”

“…1a) has already been done [11] and is shown for the sake of comparison. According to literature, the anodic peaks at low potentials have been attributed to electroformation of different antimony species with soluble species formation up to finally yield the Sb 2 O 3 oxide [4,5], while the steady-state current obtained in the 0.9 V-3.5 V potential range has been attributed to the anodic growth of a Sb 2 O 3 film by an ionic conduction mechanism caused by a ''highfield" that drives the ionic migration as in typical ''valve" metals [11]. However, no clear explanation of the processes taking place at potentials higher than ca.…”

“…1.0 V, the optical response (open symbols) shows the typical changes associated with the growth of an oxide film [24][25][26][27], but at potentials exceeding around 4.5 V (full triangles) the W-D response shows an increasing scattering and the formation of oxygen bubbles on the surface is seen. The evaluation of optical properties as well as thickness of the anodic oxide film at high potentials has been made by employing galvanostatic methods, as reported recently [11].…”

“…The electrochemical behaviour of pure antimony has been mainly studied in sulphuric acid solutions [2][3][4][5][6][7][8], although some studies in other media as phosphoric acid or phosphate solutions [9][10][11] are found. In concentrated sulphuric solutions, Laihonen et al [3] have established that Sb dissolves via the formation of trivalent antimony species (SbO + ) and even though the electrode potential is by far more positive than the equilibrium potential of the Sb(V)/Sb(III) couple, no pentavalent Sb species are formed.…”

“…Electrochemical impedance spectroscopy was also employed in order to characterize the transport processes in the anodic films formed in sulphuric acid solutions [7,8]. More recently, the kinetics of growth, morphology and stability of antimony oxide films in buffered phosphate electrolytes by electrochemical methods, ellipsometry and atomic force microscopy, has been reported [11].…”