Electrodeposition of Bi–Te Thermoelectric Material in Ethylene Glycol-BiCl₃–TeCl₄ Non-Aqueous Solution

Abstract

The electrodeposition of bismuth–tellurium thermoelectric material was investigated by galvanostatic and potentiostatic electrolysis in ethylene glycol (EG)-BiCl₃–TeCl₄ non-aqueous solutions at 393 K. Controlling the molar ratio of BiCl₃ to TeCl₄ in the bath and the electrolysis conditions, the Bi–Te alloys with various compositions were electrodeposited. The composition of the electrodeposit obtained in the 97.50 mol%EG-2.45 mol%BiCl₃–0.05 mol%TeCl₄ bath with the BiCl₃ to TeCl₄ molar ratio of 50:1 at the current density of 20 A·m⁻² was 40.14 mol%Bi–59.86 mol%Te and close to that of Bi₂Te₃. This electrodeposit exhibited a n-type thermoelectric conversion for the given temperature difference and its Seebeck coefficient was −145 µV K⁻¹.

Fig. 7 Thermoelectric forces of 0.01 mol%Bi–99.99 mol%Te, 18.75 mol%Bi–81.25 mol%Te, and 40.14 mol%Bi–59.86 mol%Te alloy films obtained in the present study.