Electrodeposition of lanthanum in lanthanum chloride saturated AlCl3-1-ethyl-3-methylimidazolium chloride molten salts

The solubility of LaCl3 in acidic AlCl3-1-ethyl-3-methylimidazolium chlorid e (AlCl3-EMICl) ambient temperature melts at 298 K increases as the acidity of the melts increases. When LaCl3 was dissolved in the melt (molar fracti on of AlCl3, N = 0.667), Raman spectra of AlCl4- and Al2Cl7- anion were obs erved. From these results, the dissolution reaction in the acidic melts is thought to be: 3Al(2)Cl(7)(-) + LaCl3 reversible arrow La(III)+ 6AlCl(4)(-) . Electrochemical measurements and potentiostatic electrolysis were perform ed in various LaCl3 saturated AlCl3-EMICl melts. The electrodeposits obtain ed at more negative potential than - 0.18 V versus Al(III)/Al in a LaCl3 sa turated acidic melt (N = 0.667) were pure aluminum metal. It was suggested that lanthanum metal electrodeposits at around - 1.95 V in the LaCl3 satura ted melt (N = 0.667) after addition of excessive LiCl and 50 mmol kg (-1) o f SOCl2. (C) 2001 Elsevier Science Ltd. All rights reserved.