Chemical Route to Yb₁₄MgSb₁₁ Composites with Nanosized Iron Inclusions for the Reduction of Thermal Conductivity

Abstract

The rapid rise of atmospheric CO2 has spurred keen research interest in sustainable energy technologies including thermoelectric materials which can reliably and robustly turn heat directly to electricity. Yb14MnSb11 has been the material of intense study because of its high thermoelectric figure of merit, zT. A structural analogue, Yb14MgSb11, is also of interest as it has a higher average zT ( ) and a comparable peak zT (1.3 vs 1.2) to Yb14MnSb11. We have shown that Yb14MgSb11 can be composited with micron-sized iron particles with significant improvements to the thermoelectric power factor (PF) and mechanical properties. In this work, we successfully employ a rapid high-temperature in situ reaction to create well-dispersed nanoscale (<100 nm) iron inclusions in the bulk Yb14MgSb11 matrix via the decomposition of FeSb2 into Fe and Sb. The incorporation of nanoscale iron into Yb14MgSb11 further reduces the lattice thermal conductivity (κl), when compared to the previously published micron iron composites, due to an increase in phonon scattering. As a result of the synchronous decrease in thermal conductivity and resistivity, the 7.3 vol % Fe sample retains the zT of Yb14MgSb11 while achieving a 43% PF improvement.

Atomically Precise Ni–Pd Alloy Carbonyl Nanoclusters: Synthesis, Total Structure, Electrochemistry, Spectroelectrochemistry, and Electrochemical Impedance Spectroscopy

“… 8 In this sense, the study of larger and larger molecular clusters such as HNMCCs represents an exciting frontier that could create a bridge to contemporary nanomaterials for electronic and electrochemical applications. 9 − 13 …”

“…In particular, molecular Fe and Co carbonyl clusters have been employed as electrocatalysts for the two-electron reduction of two protons to molecular hydrogen and for the two-electron reduction of H + and CO 2 to formate. , The molecular nature of these clusters allows us to gain detailed structural insight into the electrocatalytic active species and into the overall mechanism occurring in the catalyst microenvironment . In this sense, the study of larger and larger molecular clusters such as HNMCCs represents an exciting frontier that could create a bridge to contemporary nanomaterials for electronic and electrochemical applications. − …”

Deciphering Defects in Yb2–xEuxCdSb2 and Their Impact on Thermoelectric Properties

“… zT as a function of temperature for leading p-type Zintl phases, Yb 1.64 Eu 0.36 CdSb 2 , Eu 2 Zn 0.98 Sb 2 , YbZn 2 Sb 2 , Yb 14 MgSb 11 , and Yb 14 MnSb 11. Yb 1.6 Eu 0.4 CdSb 2 from this work (purple) gives a higher zT across the low-temperature range (300–525 K) than any other material shown.…”

On the Ytterbium Valence and the Physical Properties in Selected Intermetallic Phases

“…Yb 14 MgSb 11 has, compared to its Mn-containing analogue, an increased Seebeck coefficient which leads to an increase of 45% in the figure of merit ( zT = 1.02 at 1075 K) at the same temperature . The addition of iron leads to the formation of nanosized inclusions, which lead to an even further increase of zT . , Yb 14 MnBi 11 and Yb 14 MgBi 11 are both metallic in nature, and Yb 14 MgBi 11 has an increased carrier concentration in comparison to the isostructural antimonide which compensates potential improvements of the thermoelectric properties. Overall, the zT values of both compounds reach ∼0.2 at 875 K …”

“…403 The addition of iron leads to the formation of nanosized inclusions, which lead to an even further increase of zT. 404,405 Yb 14 MnBi 11 and Yb 14 MgBi 11 are both metallic in nature, and Yb 14 MgBi 11 has an increased carrier concentration in comparison to the isostructural antimonide which compensates potential improvements of the thermoelectric properties. Overall, the zT values of both compounds reach ∼0.2 at 875 K. 406 The MT 2 X 2 compounds that adopt the trigonal Ce 2 O 2 S type structure (space group P3m1) with the general composition M II T II 2 Pn 2 can also be considered as valence precise Zintl phases.…”