Characteristics of an electrochemical reduction of Ta2O5 for the preparation of metallic tantalum in a LiCl–Li2O molten salt

Preparation of metallic niobium from niobium pentoxide by an indirect electrochemical reduction in a LiCl-Li2O molten salt

“…The standard decomposition potentials of pure LiCl, Li 2 O, Nb 2 O 5 and LiNbO 3 at 650 • C can be calculated to 3.46, 2.47, 1.55 and 1.90 V, respectively [7]. The cell voltage (2.47-3.46 V) for a selective decomposition of Li 2 O to produce Li metal without a decomposition of LiCl was suggested in our previous work [7][8][9]. In this cell voltage, Li metal and O 2 gas are produced by the electrolysis of Li 2 O at the cathode and the anode, respectively.…”

“…And then, the O 2-ion is eventually evolved as oxygen gas from the anode surface [7]. The anode potential gradually increases due to not only a decrease in the Li 2 O concentration of the electrolyte bulk by Li 2 O electrolysis, but also an oxidation of the Pt electrode surface [9].…”

“…The final sample was kept in a glove box under an inert Ar atmosphere. Ta metal during an electrolytic reduction of Ta 2 O 5 in a LiClLi 2 O molten salt [9]. Jiang et al [13] reported the formation of CaTiO 3 during an electrochemical reduction of TiO 2 in a CaCl 2 melt.…”

“…This conventional process for the production of niobium has several drawbacks from viewpoint of an energy saving, waste management and simplicity. Recently, an electrochemical reduction process has been focused on to prepare various metallic particles [2][3][4][5][6][7][8][9]. Various molten salt systems have been used for an electrolytic production of pure metal powders from their oxides.…”

“…Our research group has investigated the indirect electrolytic reduction of metal oxides to prepare metallic particles in a LiClLi 2 O molten salt [7][8][9][10]. The novel concept of the electrolytic reduction process is to reduce the metal oxides to their metallic forms by combining an electrode reaction and a chemical reaction.…”