Electrochemical deposition of superconductor alloy precursor in a low melting molten salt medium

Abstract

The applicability of the room temperature molten salt medium based on the 1-methyl-3-ethylimidazolium chloride/AlCl3 (MeEtImCl/AlCl3) system for the deposition of superconductor alloy precursors (Bi-Sr-Ca-Cu) was investigated. Problems of poor solubility of the constituent metal salts in the neutral melt and aluminium codeposition in the acidic melt were identified for the use of the chloroaluminate room temperature molten salt. Thus, a novel all-chloride molten system (MeEt-ImCl) was developed in the present work and used at 120°C. Cyclic voltammetry was used to investigate the suitability of Pt, Al, Ti, Cu and Ag as substrate for alloy deposition and aluminium was found to be the best for depositing alkaline earth metal alloys. The working deposition conditions were a constant potential of -1.72 V for 75 s in an electrolytic bath containing BiCl3 (0.068 mol), SrCl2 (0.50 mol), CaCl2 (0.18 mol) and CuCl2 (0.050 mol) in 1 kg MeEtImCl (6.83 mol). The compositions of the electrodeposits obtained were in close agreement with the mole ratios of the Bi-Sr-Ca-Cu superconductor alloy precursor.