Combinatorial aerosol deposition of bismuth-antimony thermoelectric coatings with tunable composition

Aerosol deposition (AD) is commonly employed as a material processing step to generate coatings on substrates. In AD, aerosolized powders are passed through a nozzle and impacted at supersonic speeds onto the substrate. Plastic deformation of particles upon impact yields coatings with near bulk density. One key, unexploited advantage of aerosol processing is the ability to homogeneously mix disparate materials in the gas phase without concern over chemical compatibility or separation. Here, by using a custom-made voice-coil hopper injection (VHI) system for tunable injection of elemental powders, we demonstrate that AD can be applied directly in materials synthesis, depositing elemental precursor powders into homogeneous, dense coatings at adjustable atomic ratios. We examine the potential of combinatorial AD within the context of binary bismuth- antimony thermoelectric coating synthesis, adjusting the bismuth-antimony atomic ratio from 0.88:0.12, 0.75:0.25, to 0.5:0.5 and demonstrating that strongly adhered bismuth-antimony coatings can be produced via AD. Post-annealing is shown to yield solid bismuth-antimony solutions with thermoelectric properties approaching coatings produced by AD of pre-made, bismuth-antimony powders. Experiments are supplemented by molecular dynamics simulations of Bi and Sb nanoparticle sequential deposition, which reveal that the coating consolidation proceeds by plastic deformation and fracture of particles upon deposition.

Automated summary

Aerosol deposition (AD) is a commonly used material processing technique for generating dense coatings. One advantage of AD is the homogeneous mixing of different materials in the gas phase. In this study, the researchers demonstrate the application of AD in materials synthesis by directly depositing elemental precursor powders into adjustable atomic ratio coatings. They successfully synthesized bismuth-antimony coatings with various atomic ratios and achieved solid solutions with desirable thermoelectric properties after annealing. Molecular dynamics simulations further revealed the plastic deformation and fracture mechanisms during coating consolidation.