Electrodeposition of tantalum and aluminium in ionic liquid [Py1,4] TFSA

Abstract

Ionic liquids, especially air and water stable ones, have attracted extensive attention since they have outstanding physical properties. In addition to their chemical and thermal stability, air and water stable ionic liquids have a large electrochemical window up to ±3 V (v. NHE), and hence they give, in principle, access to the electrodeposition of reactive elements which were only accessible from high temperature molten salts in the past. The present paper deals with the electrodeposition of Ta and Al in the air and water stable ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl) amide ([Py1,4]TFSA). The results show that compact Ta films can be electrodeposited in the employed ionic liquid containing TaF5 as a source of Ta at 200°C. It was also demonstrated that adherent Al layers can be made in [Py1,4] TFSA. Depending on the concentration of AlCl3 in the employed ionic liquid, nano- and microcrystalline Al can be obtained.