1. (a) Powder XRD patterns of sintered samples with powders treated in different atmospheres, and (b) XRD patterns of bulk samples measured perpendicular to the sintered pressing direction

2. FESEM images for In-Ar sample along the direction (a) perpendicular and (b) parallel to sintering pressure

3. (a) Backscattered electron images, (b) Bi, (c) Sb, and (d) Te elemental distribution mappings on the polished surface of In-Ar sample via EDS along the direction perpendicular to the sintering pressure

4. Formation energy with complex defects presented in Bi_0.5Sb_1.5Te₃ alloys at different Te chemical potentials

5. Temperature dependence of (a) electrical conductivity, (b) Seebeck coefficient, (c) power factor for samples treated with different atmospheres along the direction perpendicular to the sintering pressure, (d) relationship between Seebeck coefficient and carrier concentration (Pisarenko curve) at room temperature for Bi-Sb-Te alloy

6. Temperature dependence of (a) total thermal conductivity, (b) sum of lattice thermal conductivity and bipolar thermal conductivity, (c) thermoelectric merit ZT for samples treated with different atmospheres along the direction perpendicular to the sintering pressure

Table 1. Orientation factor (F), conductivity (σ), Seebeck coefficient (S), carrier concentration (n), mobility (μ), total thermal conductivity(κ), effective mass (m^*/m₀), and thermoelectric value ZT of the samples treated with different atmospheres at room temperature and average thermoelectric value ZT_ave