Fig. 2. Characterization of structure and composition of Bi₂Te₃ thick films prepared by the powder direct molding method.

a SEM images of the surface and cross-sectional microstructure of samples annealed at 440 °C for 90 min. b Compressive strength of Bi₂Te₃ as a function of compression strain. The powder direct molding and commercial zone melting samples are compared. c Atomic percentage of Te content in Bi₂Te₃ thick films prepared at different annealing temperatures (360, 400, 440, and 450 °C) and times (70, 90, and 110 min), characterized by EDS. d XRD spectra of Bi₂Te₃ thick films annealed at different annealing temperatures for 90 min. e XRD spectra of Bi₂Te₃ thick films annealed at 440 °C for different times.