Zintl-phase compounds have been extensively studied in recent years due to their phonon-glass and electron-crystal structure. As a ZrBeSi-type Zintl-phase compound, SrCuSb exhibits both high electrical transport properties and thermal conductivity because of the fully occupied anionic framework. In this work, the thermoelectric properties of SrCuSb were refined by Sr self-doping. The increased Sr content not only suppressed the secondary phase SrCu 2 Sb 2 but also lowered the carrier contribution to the thermal conductivity. A zT value of ∼0.36 was achieved for Sr 1.05 CuSb at 700 K. To further decrease the thermal conductivity, Ba was introduced to the alloy at the Sr site. Benefiting from the point defect scattering, the lattice thermal conductivity was reduced to ∼0.7 W K −1 m −1 at 760 K for the Sr 0.75 Ba 0.3 CuSb sample. Finally, a peak zT of ∼0.5 was obtained for Sr 0.75 Ba 0.3 CuSb at 773 K.
Mechanically robust thermoelectric materials are essential for designing reliable thermoelectric modules. The Bi 2 Te 3 -based alloys show intrinsically poor mechanical properties, thus improving their mechanical performance is of great significance. In this work, the composites of p-type Bi 0.4 Sb 1.6 Te 3 and n-type Bi 2 Te 2.7 Se 0.3 (CuI) 0.003 with different K 2 Ti 6 O 13 whiskers contents are prepared. Due to the grain refinement and the whiskers strengthening mechanism of crack deflection, whiskers pulling out, and whiskers bridging, the mechanical properties of Bi 2 Te 3 -based materials are significantly improved. In addition, the zT value of the Bi 2 Te 3based alloys remains almost unchanged compared with the pristine sample. Our study indicates that whiskers strengthening is an effective route to enhance the mechanical properties of thermoelectric materials.
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