Electroreduction of tantalum fluoride in a room temperature ionic liquid at variable temperatures.

The present paper deals with the electroreduction of TaF5 in the room temperature ionic liquid 1-buty-1-methyl-pyrrolidinium bis(tri-fluoromethylsulfonyl)imide ([BMP]Tf2N) at different temperatures for the sake of electrodeposition of tantalum. The study was carried out using cyclic voltammetry and chronoamperometry measurements complemented by SEM-EDAX and XRD investigations. In situ scanning tunneling microscopy and I-U tunneling spectroscopy were also utilized for characterization of the electrodeposits. The results show that, in addition to the formation of insoluble compounds, Ta can be electrodeposited in the ionic liquid ([BMP]Tf2N) containing 0.5 M TaF5 at 200 degrees C on polycrystalline Pt and Au(111) electrodes. By addition of LiF to the electrolyte, the quality and the adherence of the electrodeposit were found to be improved. An in situ I-U tunneling spectrum with about 300 nm thickness of the electrodeposit shows metallic behaviour indicating the formation of elemental tantalum. Moreover, the XRD patterns of the electrodeposit, obtained potentiostatically at -1.8 V (vs. Pt) in ([BMP]Tf2N) containing 0.25 M TaF5 and 0.25 M LiF on Pt electrode at 200 degrees C, show the characteristic patterns of crystalline tantalum.

[1]  Frank Endres,et al.  Electrodeposition of nanoscale silicon in a room temperature ionic liquid , 2004 .

[2]  A. Savall,et al.  Electrodeposition processes of tantalum(V) species in molten fluorides containing oxide ions , 2002 .

[3]  F. Endres,et al.  Nanoscale electrodeposition of germanium on Au(111) from an ionic liquid: an in situ STM study of phase formation , 2002 .

[4]  A. Robin,et al.  Corrosion behavior of niobium, tantalum and their alloys in hot hydrochloric and phosphoric acid solutions , 2000 .

[5]  C. Friedrich,et al.  The corrosion of tantalum in oxidizing sub- and supercritical aqueous solutions of HCl, H2SO4 and H3PO4 , 1999 .

[6]  G. G. Peterson,et al.  Low-temperature chemical vapor deposition of tantalum nitride from tantalum pentabromide for integrated circuitry copper metallization applications , 1999 .

[7]  A. Robin.  Corrosion behavior of niobium, tantalum and their alloys in boiling sulfuric acid solutions , 1997 .

[8]  P. Chamelot,et al.  Voltammetric studies of tantalum electrodeposition baths , 1994 .

[9]  A. Dutra,et al.  Use of pulse currents for tantalum electrowinning in molten fluorides , 1993 .

[10]  F. Lantelme,et al.  Electrodeposition of Tantalum in NaCl ‐ KCl ‐ K 2TaF7 Melts , 1992 .

[11]  J. Selman,et al.  Polarization Effects on Meniscus Characteristics in Molten Carbonate , 1992 .

[12]  G. Haarberg,et al.  Electrochemical properties of metal-molten salt mixtures , 1989 .

[13]  P. Paschen,et al.  Tantalum—processing, properties and applications , 1989 .

[14]  G. W. Mellors,et al.  Electrodeposition of Coherent Deposits of Refractory Metals V . Mechanism for the Deposition of Molybdenum from a Chloride Melt , 1967 .

[15]  G. W. Mellors,et al.  Electrodeposition of Coherent Deposits of Refractory Metals I . Niobium , 1967 .

[16]  G. W. Mellors,et al.  Coherent Coatings of Refractory Metal , 1966, Science.

[17]  W. Reinhart,et al.  The Electrodeposition of Coherent Deposits of Refractory Metals II . The Electrode Reactions in the Deposition of Tantalum , 1966 .

[18]  G. W. Mellors,et al.  The Electrodeposition of Coherent Deposits of Refractory Metals III . Zirconium , 1966 .