SULFONE-BASED ELECTROLYTES FOR ALUMINUM ELECTRODEPOSITION

We developed new electrolytes for aluminum deposition based on AlCl3/d ialkylsulfones (XSO(2)) mixtures usable in the 40-150 degrees C temper atures range along the melting point of the sulfone choosen. NMR study of these electrolytes showed that they contain AlCl4- Al(XSO(2))(2)(3 +) and 1:1 molecular adducts AlCl3-XSO(2); this latter Al species is f ormed at the expense of Al(XSO(2))(3)(3+), especially in diethylsulfon e and dipropylsulfone-based electrolytes. The Al species responsible f or aluminum deposition has been shown to be Al(XSO(2))(3)(3+). Al depo sits formed from AlCl3/XSO(2) electrolytes exhibit fine grain size, re latively smooth surface aspect and high purity. High deposition rates (>50 mu m h(-1)) and thick Al deposits with thickness up to few hundre ds micrometers were obtained from AlCl3/dimethylsulfone at 130 degrees C.