Evaluation of Thermoelectric Properties of Ag_0.366Sb_0.558Te

Abstract

Ternary AgSbTe 2 materials are frequently reported to show a promising thermoelectric performance, due to the intrinsically low lattice thermal conductivity and complex valence band structure. However, stoichiometric AgSbTe 2 is found to be thermodynamically unstable and would partially decompose into Ag 2 Te and Sb 2 Te 3 during thermal cycling. Instead, Ag 0.366 Sb 0.558 Te is the composition for stabilizing the single-phase according to the Ag 2 Te-Sb 2 Te 3 phase diagram, while the thermoelectric transport properties have rarely been reported and are the focus of this work. Sn/Sb substitution is found to effectively increase not only the carrier concentration from ≈5 × 10 19 cm −3 to ≈4 × 10 21 cm −3 , but also the density-of-states effective mass, leading to an enhanced Seebeck coefficient along with a decreased carrier mobility. Single parabolic band (SPB) model with acoustic phonon scattering enables a good understanding on the charge transport. The increased carrier concentration effectively suppresses the bipolar effect at high temperatures. As a result, a peak zT of ≈1.3 and an average of ≈0.9 are achieved.

Advances in thermoelectric (GeTe) x (AgSbTe2)100 – x

“…This can be effectively realized by introducing various defects, such as zero-dimensional point defects, [1][2][3][4][5][6] one-dimensional dislocations [7,8] and twodimensional interfaces, [9][10][11][12] for effectively scattering phonons and thereby reducing κ L . Moreover, the features of complex crystal structure, [13,14] liquid-like ions, [15] low sound velocity, [16] and strong lattice anharmonicity [17,18] have been demonstrated to accompany with an intrinsic low κ L , which are utilized as guiding principles for exploring novel thermoelectric materials with a superior zT .…”