Compromise between band structure and phonon scattering in efficient n-Mg3Sb2-Bi thermoelectrics

Next-generation thermoelectric cooling modules based on high-performance Mg3(Bi,Sb)2 material

“…The Bi-rich Mg 3.2 Bi x Sb 2Àx alloy is believed to possess favorable near room temperature thermoelectric performance owing to the smaller effective mass and reduced lattice thermal conductivity. 38 However, due to the narrow band gap and the strong bipolar effect of Mg 3.2 Bi 2 , the optimal compositions for thermoelectric cooling applications are roughly located in the range of 1.2 R x R 1.75 for Bi, which is confirmed by the theoretical predictions based on SPB model and literature reports in Figure 2A (see supplemental information for more details) and Figure S4. 33,37,47 The corresponding room temperature DT max of the modules based on the n-type Mg 3.2 Bi x Sb 2Àx materials in Figure S4 and p-type commercial (Sb 0.75 Bi 0.25 ) 2 (Te 0.97 Se 0.03 ) 3 can be estimated as shown in Figure 2B, where the same contact resistivity as being measured in this work was used in these calculations.…”

“…[32][33][34][35][36] Fundamentally, thermoelectric performance of this material can be optimized by tuning the band structure and carrier concentration for the purpose of applications at different temperatures. [37][38][39] Manipulation of the scattering mechanism has been identified as an effective approach to increase the carrier mobility in Mg 3 (Bi,Sb) 2 systems. 6,8,37 In the particular instance, the electrical transport properties at near room temperature can be significantly improved through the reduction of grain boundary scattering of electrons in Mg 3 (Bi,Sb) 2 .…”

Synergistic Effect of Band and Nanostructure Engineering on the Boosted Thermoelectric Performance of n‐Type Mg3+δ(Sb, Bi)2 Zintls

“…The SPB model was commonly used for evaluating the thermoelectric potential of Mg 3+ δ (Sb,Bi) 2 Zintls since it is based on the condition of acoustic phonon scattering. [ 28,57,58 ] The as‐determined κ e possesses the same trends as the σ. Figure 5c shows the determined κ l by κ l = κ – κ e , from which the lowest κ l can be achieved within the entire temperature range when x = 0.02, and the κ l achieved at high temperatures (>550 K) has reached the calculated Cahill's minimum κ l (κ l,min ) of Mg 3 Sb 1.5 Bi 0.5 .…”

Maximizing the performance of n-type Mg3Bi2 based materials for room-temperature power generation and thermoelectric cooling

“…However, one of the main reasons that limit its further wide applications is the scarcity of Tellurium (Te) element. During the past decade, some new Te-free thermoelectric candidates with high zTs, such as α-MgAgSb [22][23][24] , Mg 3 Bi 2 [25][26][27][28][29][30] , SnSe 31,32 , enable the potential replacement of Bi 2 Te 3 , in which a high power-generation performance of Mg 3 Sb 2 / MgAgSb module, with the target for harvesting low-temperature waste heat, has already been demonstrated very recently 33,34 . P-type α-MgAgSb shows the large enhancement of thermoelectric performance at the low-temperature range by suitable doping 22,35 .…”

“…P-type α-MgAgSb shows the large enhancement of thermoelectric performance at the low-temperature range by suitable doping 22,35 . Alloying with Mg 3 Bi 2 in n-type Mg 3 Sb 2 yields the optimum bandgap and simultaneously strengthens the point-defect scattering [25][26][27][28][36][37][38][39][40][41][42][43][44][45] , therefore contributing to highly competitive zTs. Moreover, a high-performance uni-couple (with p-type Bi 0.5 Sb 1.5 Te 3 ) for thermoelectric cooling has been experimentally realized 25 .…”