Galvanic and chemical deposition of bismuth powders from aqueous solutions

Deposition of bismuth powders was investigated in this work. Bi powders can be obtained from heterogeneous systems e.g., via galvanic displacement reaction by an immersion of aluminum metal into Bi(III) complexed solutions. It was shown that, on the aluminum substrate, Bi powders can be obtained from acid, close to neutral or from alkaline solutions. Bi particles obtained via galvanic deposition are predominantly dendritic. To avoid the incorporation of Bi - oxides into the final product, it is recommended that the deposition via galvanic displacement reaction from K[BiI4] or complexed Bi(III)-citrate-EDTA solutions on Al substrate is carried out in the acidic solutions in order to suppress the hydrolysis of Bi(III) ions. Alternatively, bismuth powders can successfully be produced from homogenous aqueous systems using Bi(III) complexed solutions as a source of Bi and an alkaline Sn(II) solution acting as a reducing agent of Bi(III) ions. The average particle size was about 0.25 μm for Bi powders produced from Bi(III) - citrate complexed solution using alkaline Sn(II) as a reducing agent. For Bi powders produced from K[BiI₄] solutions with Sn(II) as a reducing agent, the average particle size was estimated at about 0.65 μm.