TY - JOUR
T1 - Traversing the metal-insulator transition in a zintl phase
T2 - Rational enhancement of thermoelectric efficiency in Yb14Mn 1-xAlxSb11
AU - Toberer, Eric S.
AU - Cox, Catherine A.
AU - Brown, Shawna R.
AU - Ikeda, Teruyuki
AU - May, Andrew F.
AU - Kauzlarich, Susan M.
AU - Jeffrey Snyder, G.
PY - 2008/9/23
Y1 - 2008/9/23
N2 - For high temperature thermoelectric applications, Yb14MnSb 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 14MnSb11 and semiconducting Yb14AlSb 11. Yb14Mn1-xAlxSb11 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 me. 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 Si0.8Ge0.2 flown by NASA.
AB - For high temperature thermoelectric applications, Yb14MnSb 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 14MnSb11 and semiconducting Yb14AlSb 11. Yb14Mn1-xAlxSb11 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 me. 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 Si0.8Ge0.2 flown by NASA.
UR - http://www.scopus.com/inward/record.url?scp=53849092390&partnerID=8YFLogxK
U2 - 10.1002/adfm.200800298
DO - 10.1002/adfm.200800298
M3 - Article
AN - SCOPUS:53849092390
SN - 1616-301X
VL - 18
SP - 2795
EP - 2800
JO - Advanced Functional Materials
JF - Advanced Functional Materials
IS - 18
ER -