Preparation of Cobalt-Antimony Thermoelectric Film using Pulse Electrolysis in Ethylene Glycol-CoCl₂-SbCl₃ Non-Aqueous Solution

Abstract

The preparation of cobalt-antimony thermoelectric film using pulse electrolysis was investigated in ethylene glycol (EG)-CoCl2-SbCl3 non-aqueous solutions at 393 K. The layered structures consisting of Co rich Co-Sb alloy layers and Sb rich Co-Sb alloy layers were obtained by applying alternately the potentials for electrodepositing the former, ECo, and the latter, ESb, in the 90.0 mol%EG-9.09 mol%CoCl2-0.91 mol%SbCl3 bath, and were heat-treated at 673 K for 24 h in Ar gas atmosphere to prepare the Co-Sb alloy films with uniform composition. The composition of Co-Sb alloy film was found to be controlled by adjusting the ratio of applied duration at ECo, tCo, to one at ESb, tSb, in the potential rectangular wave used in the pulse electrolysis. At the (tSb / tCo) ratio of 7.0, the Co-Sb alloy film with the composition of 26.1 mol%Co-73.9 mol%Sb was obtained after heat treatment. This alloy film was not the CoSb3 single phase, but included it as constituent and exhibited a p-type thermoelectric conversion by the given temperature difference.