Thermoelectric, structural, and mechanical properties of spark-plasma-sintered submicro- and microstructured p-type Bi _0.5Sb _1.5Te ₃

In the last two decades, attention to alternative energy has grown dramatically. Thermoelectric energy conversion of heat from combustion systems and hot engines into electricity can be utilized for such purposes. Practical thermoelectric materials for such applications must exhibit both favorable thermoelectric and mechanical properties. Bi ₂Te ₃-based alloys are known to be the best thermoelectric materials near room temperature. The current manuscript is concerned with the mechanical and transport properties of bulk submicro- and microstructured p-type Bi _0.5Sb _1.5Te ₃ samples with carrier concentration of ∼1 × 10 ¹⁹ cm ^-3 to 3 × 10 ¹⁹ cm ^-3. Among the investigated samples, the maximal ZT values of the microstructured Bi _0.5Sb _1.5Te ₃ were found to be higher (∼0.96) compared with the submicrostructured samples (∼0.81), due to the highly anisotropic nature of the investigated microstructured alloy. Nevertheless, microhardness values were found to increase with reduction of grain size (85 Hv to 145 Hv for the submicrostructured, compared with ∼60 Hv for the microstructured samples).