Electrodeposition of Bi_1-xSb_xFilms and 200-nm Wire Arrays from a Nonaqueous Solvent

Films and 200-nm wire arrays of Bi 1- x Sb x alloys, one of the best known low-temperature thermoelectric materials, have been obtained by electrodeposition without the need for complexing the Sb cations in solution or further thermal treatment after deposition. The process consists of reduction of Bi 1- x Sb x directly from a solution of Bi(NO 3 ) 3 · 5H 2 O and SbCl 3 in dimethyl sulfoxide at 25 °C on Pt electrodes. The electrodeposited films are polycrystalline and single phase under slow growth conditions, but two phases are observed under rapid growth conditions (more negative potentials) and for films with roughly equal amounts of Bi and Sb. 200-nm wire arrays of Bi 1- x Sb x were grown under similar conditions using porous alumina as a template. Arrays of dense, continuous, and highly crystalline Bi 0.84 Sb 0.16 wires (close to the predicted optimum composition for thermoelectric applications) have been fabricated successfully at deposition potentials of −0.28 V vs Ag/AgCl from a solution of 0.050 M Bi and 0.030 M Sb in DMSO.