Electrodeposition of Niobium from the CsBr-KBr-NbBr ₃ Melt

Abstract

The CsBr-KBr-NbBr 3 melt was proposed as a promising electrolyte for obtaining high-quality niobium coatings. This melt is less aggressive and provides a higher deposition rate of dense Nb layers compared to the fluoride and chloride electrolytes commonly used for electrodeposition of niobium. The effect of temperature and cathode current density during electrodeposition from the CsBr-KBr-NbBr 3 melt on the structure and morphology of the Nb coatings was investigated. The conditions for the deposition of thick, dense, well-adherent Nb coatings were found. Cyclic voltammetry was used to study the regularities of the cathode process in the CsBr-KBr (57 mol% CsBr − 43 mol% KBr) - NbBr 3 melts containing 0.4, 1.6, and 4.45 wt% Nb in a temperature range of 893 to 1013 K. A two-stage mechanism with the participation of Nb(III) and Nb(II) ions was proposed and the effective diffusion coefficient of niobium cations in the bromide melt was estimated based on a comparison of data obtained by cyclic voltammetry and numerical simulation.