Enhanced thermoelectric performance in the zintl antimonides (Ca,RE)9Cd4Sb9 (RE = rare-earth metal). Synergy between increased structural complexity and drive towards optimized chemical bonding

Synthesis and Crystal and Electronic Structures of the Zintl Phase Sr21Cd4Sb18

“…The structures of several series of compounds in the ternary systems AE-T-Pn systems (AE = Ca, Sr, Ba, Eu, and Yb; T = Mn, Zn, and Cd; Pn = As, Sb, and Bi) can also be understood based on the Zintl concept. As shown by our group, as well as by some other teams, ternary pnictides that are commonly referred to as "2-1-2" phases [18][19][20][21], "9-4-9" phases [22][23][24][25][26][27], "14-1-11" phases [8,9,[28][29][30][31][32][33][34], "10-1-9" phases [35][36][37], and "11-1-9" phases [38][39][40] exhibit a very rich structural chemistry. Many of the above-mentioned compounds also have interesting magnetic and transport properties.…”

Exploiting the fraternal twin nature of thermoelectrics and topological insulators in Zintl phases as a tool for engineering new efficient thermoelectric generators

“…This approach thus allows for the independent tuning of S 2 σ and κ L being the electronic and phonon contributions to zT , respectively. Similarly, another powerful parameter that can be invaluable to understanding the potential of these materials is the thermoelectric quality factor B 68,138 which is defined as:where k B , h , e , μ w , and κ L represent Boltzmann's constant, Planck's constant, electronic charge, weighted mobility, and lattice thermal conductivity, respectively. It is immediately clear from this expression that B ∝ μ w / κ L , such that μ w carries the same importance as κ L and as such increasing the magnitude of μ w is as important as achieving an ultra-low κ L .…”

“…This approach thus allows for the independent tuning of S 2 s and k L being the electronic and phonon contributions to zT, respectively. Similarly, another powerful parameter that can be invaluable to understanding the potential of these materials is the thermoelectric quality factor B 68,138 which is defined as:…”

“…Some other notable Zintl phases with excellent TE properties include Ca 9 Zn 4+ x Sb 9 , 52 YbCd 2– x Zn x Sb 2 , 53 Ca x Yb 1– x Zn 2 Sb 2 , 54 Ca 5 Al 2 Sb 6 , 55 BaGa 2 Sb 2 , 56,57 etc. 58–63 In recent years our group has contributed significantly to the discovery and characterization of several other families of Zintl phases, including AE 2 CdP 2 , 64 Eu 3 InAs 3 , 65 Ca 14 AlBi 11 , 66 Ca 10 M Sb 9 ( M = Ga, In, Mn, Zn), 67 Ca 9– x RE x Cd 4 Sb 9 , 68 and Ca 10 RE CdSb 9 , 69 among many others ( RE = rare-earth metal). 70–76…”