Electrodeposition of Sb-Te Alloy in AlCl₃-NaCl-KCl Molten Salt

Abstract

The Electrodeposition of Sb-Te alloy was carried out in AlCl₃-NaCl-KCl molten salt containing SbCl₃ and TeCl₄ at 423 K by constant potential electrolysis. The voltammogram on a glassy carbon (GC) electrode in a melt containing 1.0×10⁻² kmol m⁻³ SbCl₃ and 1.0×10⁻² kmol/m³ TeCl₄ revealed the cathodic current waves at 1.5, 1.1, and 0.9 V vs. Al/Al(III). A stable Sb-Te alloy deposit was obtained at 0.85 V in the melt containing SbCl₃ and TeCl₄. At the higher concentration ratio of the Sb(III) to (Sb(III) + Te(IV)), a good linear relation was found between the atomic ratio of Sb in the deposit and the concentration ratio of Sb (III) in the melt. The Sb-Te alloy deposit of atomic ratio of 38:62% which was assume to be suitable for a thermoelectric device was obtained with the molten salt containing 7.0×10⁻³ kmol/m³ SbCl₃ and 1.0×10⁻² kmol/m³ TeCl₄. The XRD pattern of the deposit corresponds to that of Sb₂Te₃ intermetallic compound. The deposit had homogeneous disk-like granule with the disk size of about 10 μm.