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This work reports on the properties of polyaniline (PANI) films electrochemically synthesised onto indium tin oxide (ITO) coated glass substrate from a mixed solution of 0.1 M aniline with three different types of supporting electrolytes: HNO3, H2SO4and H3PO4. In order to investigate the effect of dopant on the behaviour of polyaniline different techniques have been employed. These characterisations were made using photoelectrochemical, FTIR and Raman spectroscopies, field-emission scanning electron microscopy, UV–vis spectroscopy, diffuse reflectance spectrophotometry and photoluminescence techniques. The potocurent transients show a change of PANI films conductivity from p-type to n-type by changing the supporting electrolytes. The FTIR technique and Raman spectroscopy confirmed the formation of PANI thin film on ITO substrates. The morphology of the electropolymerised PANI thin films is closely related to the supporting electrolytes. Compact and spongy morphologies were observed for PANI films deposited in different supporting electrolytes. The optical measurements show an optical transmittance in the visible region, with variations depending on the nature of electrolytes. [ABSTRACT FROM AUTHOR]

Co-Ni alloys thin films were electrodeposited on Ru substrates from a chloride-saccharin bath at pH 3.8 and the effects of adding saccharin to the bath on the electrochemical deposition, corrosion resistance, chemical composition, physical and magnetic properties of the deposits were investigated. The analytical techniques of cyclic voltammetry (CV), potentiodynamic polarisation, electrochemical impedance spectroscopy (EIS), atomic absorption spectroscopy (AAS), atomic force microscopy (AFM), X-ray diffraction and hysteresis curves were applied to assess the codeposition process, and determine corrosion resistance, composition, morphology, nanocrystallinity and magnetic properties. Effectively, CV measurements revealed that the addition of saccharin in the electrolytic bath modifies the deposition process and an anomalous codeposition takes place; this enhanced the Co percentage in the Co-Ni deposits. Saccharin addition also increases the double layer capacitance and decreases the charge transfer resistance. On the other hand, the Tafel plots show a higher corrosion resistance for the deposits obtained from a bath with saccharin than those obtained from a bath without it. Furthermore, the presence of the saccharin in the bath also causes notable changes in the morphology and structure characteristics of deposits. In addition, it was found that the additive influences the magnetic properties of Co-Ni alloy thin films. The coercivity and magnetisation saturation are diminished for Co-Ni films prepared from electrolytes with addition of saccharin. [ABSTRACT FROM AUTHOR]

The electrocrystallisation of Co, Ni and Co-Ni alloys on ruthenium surface from chloride baths has been studied by cyclic voltammetry and chronoamperometry measurements. The structural and magnetic properties were studied by X-ray diffraction and alternating gradient force magnetometer techniques respectively. The Co-Ni alloys were deposited from solution with molar ratios (Co/Ni) of 5:1, 1:1 and 1:5. From cyclic voltammetry measurements, for all molar ratios for electrodeposited Co-Ni, preferential deposition of Co occurs and anomalous codeposition takes place. Therefore, variation in the composition of thin films alloy is possible depending on the deposition potential. The Scharifker and Hills model was employed to analyse the current transients. For both Co and Co-Ni alloys, the nucleation was a good agreement with the instantaneous model followed by three-dimensional diffusion limited growth. However, for Ni after tmax, the nucleation process changes from progressive to instantaneous model. It is evident that the compositions of the electrolyte do not have influence on the type of nucleation for Co-Ni alloys. X-ray diffraction measurements indicate a small crystallite size with the presence of a mixture of hcp and fcc Co-Ni structures. The hysteresis loops with a magnetic field in the parallel and perpendicular directions showed that the easy magnetisation axis of Co-Ni thin film is in the film plane. [ABSTRACT FROM AUTHOR]