cm5b03434_si_001.pdf (2.17 MB)
High Thermoelectric Performance and Enhanced Mechanical Stability of p‑type Ge1–xSbxTe
journal contribution
posted on 2015-10-27, 00:00 authored by Suresh Perumal, Subhajit Roychowdhury, Devendra S. Negi, Ranjan Datta, Kanishka BiswasHigh thermoelectric figure of merit, zT, of ∼1.85
at 725 K along with significant cyclable temperature stability was
achieved in Pb-free p-type Ge1–xSbxTe samples through
simultaneous enhancement in Seebeck coefficient and reduction of thermal
conductivity. Sb doping in GeTe decreases the carrier concentration
due to the donor dopant nature of Sb and enhances the valence band
degeneracy by increasing the cubic nature of the sample, which collectively
boost Seebeck coefficient in the temperature range of 300–773
K. Significant thermal conductivity reduction was achieved due to
collective phonon scattering from various meso-structured domain variants,
twin and inversion boundaries, nanostructured defect layers, and solid
solution point defects. The high performance Ge0.9Sb0.1Te sample shows mechanical stability (Vickers microhardness)
of ∼206 Hv, which is significantly
higher compared to other popular thermoelectric materials such as
Bi2Te3, PbTe, PbSe, Cu2Se, and TAGS.