Electrochemical Obtaining of Thin Tellurium Coatings From Chloride Sulphate Solutions

Abstract

The possibility of electrochemical obtaining of thin tellurium coatings from a chloride-sulfate electrolyte has been investigated. The studies have been carried out in solution containing (mol/ l): 0.01 – 0.08 TeO 2 + 1.5H 2 SO 4 + 1.5HCl + 0.01 – 0.08 (NH 4 ) 2 SO 4 +1.0 gelatin. Ithas been found that with the increase in the concentration of HCl in the electrolyte from 0.5 mol/l to 4 mol/l, the cathodic deposition of tellurium accelerated, the polarization curves shifted in the positive direction. Experiments carried out in solutions containing chloride-sulfate ions show that in the initial stages of the cathodic process, chemical difficulties play the main role, and at negative potentials of the process, they are limited by diffusion polarization. At cathodic potentials up to 0.2 V, the process of tellurium electrodeposition from а chloride sulfate electrolyte is mainly accompanied by chemical polarization and effective activation energy at these potentials reaches up to 40 kJ /mol, and at a potential of 0.30–0.25 V, the process is controlled by mixed kinetics.