Synthesis of Uniformly Sized Bi0.5Sb1.5Te3.0 Nanoparticles via Mechanochemical Process and Wet-Milling for Reduced Thermal Conductivity

In this study, Bi0.5Sb1.5Te3.0 (BST) nanoparticles (NPs) with high crystallinities were synthesized via a mechanochemical process (MCP). X-ray diffraction (XRD), and Raman and X-ray photoelectron spectroscopy (XPS) spectra of the BST NPs showed that the Bi, Sb, and Te powders successfully formed BiSbTe phase and transmission electron microscopy (TEM) images, verifying the high crystallinity and smaller size, albeit agglomerated. The as-synthesized BST NPs with agglomerated clusters were ground into smaller sizes of approximately 41.8 nm with uniform distribution through a simple wet-milling process during 7 days. The thermal conduction behaviors of bulk alloys fabricated by spark plasma sintering (SPS) of the BST NPs were studied by comparing those of samples fabricated from as-synthesized BST NPs and a BST ingot. The thermal conductivities (kappa) of the BST nanocomposites were significantly reduced by introducing BST NPs with smaller grain sizes and finer distributions in the temperature range from 300 to 500 K. The BST nanocomposites fabricated from wet-milled BST NPs offered ultralow kappa values of 0.84 W m(-1) K-1 at approximately 398 K.

Automated summary

In this study, high crystallinity Bi0.5Sb1.5Te3.0 (BST) nanoparticles (NPs) were successfully synthesized via a mechanochemical process, and their sizes were further reduced and uniformly distributed through a wet-milling process. The BST nanocomposites fabricated from BST NPs with smaller grain sizes and finer distributions exhibited significantly reduced thermal conductivities. Wet-milled BST NPs showed ultralow thermal conductivity values at approximately 398 K, demonstrating their potential for thermoelectric applications.