Preparation and characterization of Bi0.4Te3.0Sb1.6 nanoparticles and their thin films

In this article, we perform a preliminary study to assemble micro-size thermoelectric devices with low-cost fabrication by a preparation of nanoparticles and their thin films. Bi0.4Te3.0Sb1.6 nanoparticles with an average size of approximately 50 nm are fabricated by a beads-milling method. The nanoparticle solution is prepared by mixing with toluene and a surfactant, and thin films with 1 μm thick are deposited on Al2O3 substrates by a printing method. The thin films are sintered at temperatures ranging from 300 to 500 °C for 60 min in hydrogen ambient. We investigate the thin film structures and the thermoelectric properties at room temperature. As the sintering temperature increases, hexagonal-shaped crystals are grown on the film surface while the atomic composition is almost constant throughout all the sintering temperatures. The XRD patterns indicate that all the nanoparticle thin films are found to mostly exhibit the same XRD intensities and have multiple peaks correspond to each other. The in-plane electrical conductivity of the thin films increases but the Seebeck coefficient decreases as the sintering temperature increases. As a result, the best performance of the thermoelectric power factor of 1.3 μW/(cm K2) is achieved at a sintering temperature of 350 °C.