Premium
Thermoelectric Properties and Electronic Structure of the Zintl‐Phase Sr 3 AlSb 3
Author(s) -
Zevalkink Alex,
Pomrehn Gregory,
Takagiwa Yoshiki,
Swallow Jessica,
Snyder G. Jeffrey
Publication year - 2013
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201300518
Subject(s) - thermoelectric effect , zintl phase , band gap , materials science , doping , seebeck coefficient , electrical resistivity and conductivity , electronic band structure , phase (matter) , thermoelectric materials , electronic structure , thermal conductivity , effective mass (spring–mass system) , condensed matter physics , crystallography , crystal structure , chemistry , optoelectronics , thermodynamics , physics , organic chemistry , quantum mechanics , composite material
The Zintl‐phase Sr 3 AlSb 3 , which contains relatively earth‐abundant and nontoxic elements, has many of the features that are necessary for good thermoelectric performance. The structure of Sr 3 AlSb 3 is characterized by isolated anionic units formed from pairs of edge‐sharing tetrahedra. Its structure is distinct from previously studied chain‐forming structures, Ca 3 AlSb 3 and Sr 3 GaSb 3 , both of which are known to be good thermoelectric materials. DFT predicts a relatively large band gap in Sr 3 AlSb 3 ( E g ≈1 eV) and a heavier band mass than that found in other chain‐forming A 3 MSb 3 phases (A=Sr, Ca; M=Al, Ga). High‐temperature transport measurements reveal both high resistivity and high Seebeck coefficients in Sr 3 AlSb 3 , which is consistent with the large calculated band gap. The thermal conductivity of Sr 3 AlSb 3 is found to be extremely low (≈ 0.55 W mK −1 at 1000 K) due to the large, complex unit cell (56 atoms per primitive cell). Although the figure of merit ( zT ) has not been optimized in the current study, a single parabolic band model suggests that, when successfully doped, zT ≈ 0.3 may be obtained at 600 K; this makes Sr 3 AlSb 3 promising for waste‐heat recovery applications. Doping with Zn 2+ on the Al 3+ site has been attempted, but does not lead to the expected increase in carrier concentration.