Enhanced thermoelectric properties of the Zintl phase BaGa₂Sb₂via doping with Na or K

Abstract

ab Na-or K-doped samples of Ba 1Àx (Na, K) x Ga 2 Sb 2 were prepared by ball-milling followed by hot-pressing. The topological analysis of the electron density of BaGa 2 Sb 2 implies a polar covalent nature of the SbGa bonds in which the Sb atoms receive the electrons transferred from Ba rather than the Ga atoms.Successful doping of BaGa 2 Sb 2 with Na or K was confirmed with combined microprobe and X-ray diffraction analysis. Alkali metal doping of BaGa 2 Sb 2 increased the p-type charge carrier concentration to almost the predicted optimum values ($10 20 h + cm À3) needed to achieve high thermoelectric performance. With increasing alkali metal concentration, electronic transport was shifted from nondegenerate semiconducting behaviour observed for BaGa 2 Sb 2 to degenerate one for Na-or K-doped compounds. Overall, the thermoelectric figure of merit, zT, values reached up to $0.65 at 750 K, considerably higher than the undoped sample (zT $ 0.1 at 600 K), and a slight improvement relative to previously reported Zn-doped samples ($0.6 at 800 K).

Thermoelectric Properties of Zintl Phase YbMg2Sb2

“…This can be attributed to its low carrier concentration, as mentioned in the discussion of the calculation results. Such large electrical resistivity or such a high Seebeck coefficient of the pristine compound has also been observed in other materials, for example, BaGa 2 Sb 2 , 61 AgPb 18 SbTe 20 , 62 SnSe, 63 and Ca 5 M 2 Sb 6 (M = Al, Ga, and In). 33,64 Figure 4c shows the power factor of the YbMg 2 Sb 2 samples with different Na-doping concentrations, together with the results on undoped YbMg 2 Sb 2 from Guo et al 65 for comparison.…”

Achieving zT > 1 in Inexpensive Zintl Phase Ca9Zn4+xSb9 by Phase Boundary Mapping

“…Complex Zintl phases represent a large class of compounds in which many new thermoelectric materials have been found, thanks to their versatile chemistry and inherently low thermal conductivity like glasses . Zintl compounds are made up of electropositive cations (alkali, alkaline‐earth or rare earth metals) that donate their valence electrons to anions, which in turn form covalently bonded anionic structures to satisfy the valence requirement .…”

A computational assessment of the electronic, thermoelectric, and defect properties of bournonite (CuPbSbS3) and related substitutions

“…Reduction of k L can be engineered by introducing various phonon scattering sources such as nanoparticles, grain boundaries, and point defects. 4 Furthermore, some materials such as clathrates 5 , skutterudites 6 , Sb-based Zintl phases 7,8 , 1-1-2 chalcogenides 9,10 or Cu 2-…”