Enhanced Thermoelectric Performance of Zintl Phase Ca₉Zn_4+xSb₉ by Beneficial Disorder on the Selective Cationic Site

Abstract

Zintl phase compounds Ca 9 Zn 4+x Sb 9 have promising thermoelectric properties due to their complex crystal structure and tunable interstitial Zn. In this work, we prepared nominal Ca 9 Zn 4+x Sb 9 (x = 0.5, 0.6, 0.7, and 0.8) using ball milling and hot pressing. Further decreased lattice thermal conductivity was obtained by isoelectronic substitution of Eu on the selective Ca site, which is farther away from the framework of [Zn 4+x Sb 9 ] δ− for the smaller disturbance of carrier transport. Together with the intensively enhanced carrier mobility, which is attributed to the decreased effective mass and the increased interstitial Zn by inclusion of Eu, an increased peak ZT value to ∼1.05 at 773 K and an enhanced average ZT value to ∼0.73 from 300 to 823 K were achieved in Ca 6.75 Eu 2.25 Zn 4.7 Sb 9 .

Promising Zintl-Phase Thermoelectric Compound SrAgSb

“…In the structures of the Zintl-phase compounds, the anionic framework is responsible for electrical conduction and that the cations provide a way of tuning electrical properties and providing phonon scattering. − Up to now, Zintl-phase TE materials can be roughly classified into the 14-1-11 type, , 1-2-2 type, , 3-1-3 type, , 5-2-6 type, , 9-4.5-9 type, , and so forth. In addition, the ZrBeSi-type Zintl-phase compound (such as KZnSb, Sr 2 ZnP 2 , etc. )…”

Ternary Zinc Antimonides Unlocked Using Hydride Synthesis

“…Only 12 ternary compounds from A –Zn–Sb ( A = alkali metal) systems can be found in the Inorganic Crystal Structure Database (ICSD) and literature: LiZnSb, Li 2 ZnSb, NaZnSb, NaZn 4 Sb 3 , HT -Na 1– y Zn 4– y Sb 3 , KZnSb, K 8– x Zn 18+3 x Sb 16 , K 58 Zn 122 Sb 207, Cs 8 Zn 18 Sb 28 , CsZnSb, RbZnSb, and Rb 2 Zn 5 Sb 4 . ,− ,− Among these, Cs 8 Zn 18 Sb 28 is the first antimony-based clathrate I, K 58 Zn 122 Sb 207 represents novel clathrate XI, and LiZnSb was theoretically predicted to show remarkable thermoelectric performance, e.g ., ability to convert heat into electricity and vice versa . Remarkably, inexpensive and nontoxic binaries (Zn 4 Sb 3 , Zn 13 Sb 10 , Zn 8 Sb 7 , Zn 3 Sb 2 , ZnSb) − and ternary zinc (or cadmium) antimonides (family of Ae (Zn/Cd) 2 Sb 2 compounds ( Ae = Ca, Sr, Ba, Eu, or Yb), − Eu 2 ZnSb 2 , and Ca 9‑y Eu y Zn 4+x Sb 9 ) as well as other related Zintl phases attract attention for their thermoelectric properties. , For that reason, a comprehensive investigation of the unexplored A –Zn-Sb systems is highly desirable.…”

Point defect approach to enhance the thermoelectric performance of Zintl-phase BaAgSb

“…In addition, the guest atoms or vacancies can suppress the lattice thermal conductivity by strengthening phonon scattering [22][23][24]. Indeed, high thermoelectric efficiency has been realized in some Zintl phases, such as YbZn 2 Sb 2 [25,26], Ca 9 Zn 4.5 Sb 9 [27,28], Ca 5 Al 2 Sb 6 [29], and Yb 14 MnSb 11 [30]. Our previous studies reported the thermoelectric performance of the ZrBeSi-type Zintl-phase Eu 2 ZnSb 2 , and a ZT value of 1.0 was achieved at 823 K [31].…”