Aliovalent Dilute Doping and Nano‐Moiré Fringe Advance the Structural Stability and Thermoelectric Performance in β‐Zn₄Sb₃

Abstract

Thermoelectric (TE) generators have come a long way since the first commercial apparatus launched in the 1950s. Since then, the β‐Zn4Sb3 has manifested its potential as a cost‐effective and environmentally friendly TE generator compared with the tellurium‐bearing TE materials. Although the β‐Zn4Sb3 features an intrinsically low thermal conductivity κ, it suffers from a long‐lasting structural instability issue arising from the highly mobile zinc ions. Herein, the dilute Ga dopant gives rise to the aliovalent substitution, lowers the mobile zinc ions, and optimizes the hole carrier concentration nH simultaneously. Meanwhile, the formation of nano‐moiré fringes suggests the modulated distribution of point defect that results from soluble Ga in a β‐Zn4Sb3 lattice, which elicits an ultralow lattice thermal conductivity κL = 0.2 W m−1 K−1 in a (Zn0.992Ga0.008)4Sb3 alloy. Hence, a fully dense β‐Zn4Sb3 incorporated with the dilute Ga doping reveals superior structural stability with a peak zT > 1.4 at 623 K. In this work, the aliovalent dilute doping coupled with phase diagram engineering optimizes the fluxes of moving electrons and charged ions, which stabilizes the single‐phase β‐Zn4Sb3 while boosting the TE performance at the mid‐temperature region. The synergistic strategies endow the ionic crystals with a thermodynamic route, which opens up a new category for high‐performance and thermal robust TE alloys.

High Thermoelectric Performance and Oxidation Resistance of (Na, Ga) Codoped β-Zn4Sb3 Thermoelectric Materials Prepared by the NaCl Flux

“…Through the introduction of Na and Ga, the carrier optimization is realized and results in a higher PF and ZT value in the samples with x = 0.08 and 0.12. The maximal ZT value reached 1.73 at 690 K, which is 22% higher than that of the Zn 4.1 Sb 3 (NaCl) 7 sample (1.42 at 690 K) and also better than the value reported earlier by Jen (ZT max = 1.4 at 623 K) . This work suggests that dilute Ga doping is an effective way of optimizing thermoelectric properties.…”

“…The maximal ZT value reached 1.73 at 690 K, which is 22% higher than that of the Zn 4.1 Sb 3 (NaCl) 7 sample (1.42 at 690 K) and also better than the value reported earlier by Jen (ZT max = 1.4 at 623 K). 52 This work suggests that dilute Ga doping is an effective way of optimizing thermoelectric properties. Since the average ZT (ZT ave ) values are important for thermoelectric generators, the ZT ave of all samples for different Ga doping amounts can be calculated according to the following formula…”

Enhanced thermoelectric performance of p-type Mg2Sn single crystals via multi-scale defect engineering

“…[22][23][24][25]34 It is reported that V Mg does not exist in the single-crystal region, whereas V Mg aggregates to form the dark gray regions symbolized by a striped pattern, namely, a Moiré pattern. 44,45 To examine the light gray and dark gray regions in the x = 0.020 SC, the R2 region in Fig. 2b 2b; the dark gray region was the Moiré pattern.…”

Tuning Interstitials in Fully Dense β-Zn4Sb3 Doubles Single-Leg Thermoelectric Efficiency

“…By incorporating IIIA dopants into Zn 4 Sb 3 , we have demonstrated enhanced structural stability alongside improved TE performance. 14,15 By synergistically combining cationic interstitial doping and phase diagram engineering, we have successfully developed Al−Zn 4 Sb 3 , which exhibits an improved power factor PF = S 2 σ and a 20% increase in peak zT compared to pristine Zn 4 Sb 3 . While the enhancement in the peak zT may appear subtle, the most striking outcome is the doubling of η in Al−Zn single-leg device, particularly at a temperature difference (ΔT) of 300 K. To the best of our knowledge, this research marks a significant milestone by successfully assembling the first singleleg devices using fully dense Zn 4 Sb 3 .…”