Optimization of the Electrodeposition Process of High-Performance Bismuth Antimony Telluride Compounds for Thermoelectric Applications

High-quality films of bismuth antimony telluride were synthesized by electrodeposition from nitric acid electroplating baths. The influence of a surfactant, sodium ligninsulfonate, on the structure, morphology, stoichiometry, and homogeneity of the deposited films has been investigated. It was found that addition of this particular surfactant significantly improved the microstructural properties as well as homogeneity of the films with a significant improvement in the thermoelectric properties over those deposited in the absence of surfactant. A detailed microprobe analysis of the deposited films yielded a stoichiometric composition of Bi<sub>0.35</sub>Sb<sub>1.33</sub>Te<sub>3</sub> for the films electrodeposited in the absence of surfactant and a stoichiometry of Bi<sub>0.32</sub>Sb<sub>1.33</sub>Te<sub>3</sub> for films deposited in the presence of surfactant.