High thermoelectric performance in sintered octahedron-shaped Sn(CdIn)_xTe_1+2x microcrystals

In this study, we fabricate In/Cd codoped octahedron-shape Sn(CdIn)_xTe_1+2x microcrystals with a promising thermoelectric performance by using a facile solvothermal method. The high hole-carrier concentration of pristine SnTe is significantly reduced through effective In/Cd codoping, which increases the Seebeck coefficient in a wide temperature range. Moreover, codoped In/Cd not only modifies the band structure by creating the resonance energy level at the valence band and converging light hole and heavy hole valence bands of SnTe but also provides In/Cd-rich nanoprecipitates in the matrix, leading to a high power factor of ∼26.76 μW cm^-1 K^-2 at 773 K in the sintered SnIn_0.03Cd_0.03Te_1.06. Compared with the bulk counterparts, a much lower lattice thermal conductivity is achieved over a wide temperature range because of strong phonon scattering by point defects, nanoprecipitates, lattice distortion, and grain boundaries in the sintered SnIn_xCd_xTe_1+2x (x = 3 and 4%) samples. Consequently, a high ZT of ∼1.12 is obtained at 773 K in the p-type SnIn_0.03Cd_0.03Te_1.06, suggesting that nanoprecipitate-included Cd/In codoped octahedron-shaped Sn(CdIn)_xTe_1+2x microcrystals are a convincing candidate for medium-temperature thermoelectric applications.

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