Premium
Traversing the Metal‐Insulator Transition in a Zintl Phase: Rational Enhancement of Thermoelectric Efficiency in Yb 14 Mn 1− x Al x Sb 11
Author(s) -
Toberer Eric S.,
Cox Catherine A.,
Brown Shawna R.,
Ikeda Teruyuki,
May Andrew F.,
Kauzlarich Susan M.,
Snyder G. Jeffrey
Publication year - 2008
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200800298
Subject(s) - materials science , thermoelectric effect , seebeck coefficient , figure of merit , electrical resistivity and conductivity , band gap , thermoelectric materials , effective mass (spring–mass system) , condensed matter physics , electron mobility , valence band , analytical chemistry (journal) , thermodynamics , optoelectronics , physics , chemistry , chromatography , quantum mechanics
For high temperature thermoelectric applications, Yb 14 MnSb 11 has a maximum thermoelectric figure of merit ( zT ) of ∼1.0 at 1273 K. Such a high zT is found despite a carrier concentration that is higher than typical thermoelectric materials. Here, we reduce the carrier concentration with the discovery of a continuous transition between metallic Yb 14 MnSb 11 and semiconducting Yb 14 AlSb 11 . Yb 14 Mn 1‐x Al x Sb 11 forms a solid solution where the free carrier concentration gradually changes as expected from the Zintl valence formalism. Throughout this transition the electronic properties are found to obey a rigid band model with a band gap of 0.5 eV and an effective mass of 3 m e . As the carrier concentration decreases, an increase in the Seebeck coefficient is observed at the expense of an increased electrical resistivity. At the optimum carrier concentration, a maximum zT of 1.3 at 1223 K is obtained, which is more than twice that of the state‐of‐the‐art Si 0.8 Ge 0.2 flown by NASA.