High-Temperature Transport Properties of Yb4−x Sm x Sb3

Abstract

which crystallizes in the anti-Th 3 P 4 structure type (I-43d no. 220), were synthesized via high-temperature reaction. Structural and chemical characterization were performed by x-ray diffraction and electronic microscopy with energy-dispersive x-ray analysis. Pucks were densified by spark plasma sintering. Transport property measurements showed that these compounds are n-type with low Seebeck coefficients, except for Yb 4 Sb 3 , which shows semimetallic behavior with hole conduction above 523 K. By partially substituting Yb by a trivalent rare earth we successfully improved the thermoelectric figure of merit of Yb 4 Sb 3 up to 0.7 at 1273 K.

Materials design, synthesis, and transport properties of disordered rare-earth Zintl bismuthides with the anti-Th3P4 structure type

“…Here, the PF values of Ca 3 CeBi 3 and Ca 3 PrBi 3 are about an order of magnitude lower than that of Ca 3 SmBi 3 , while Ca 3 NdBi 3 shows the least magnitude considering it manifests relatively low ρ(T ) and high α(T ). Although the magnitude of PF in Ca 3 SmBi 3 is relatively low, it is relatively higher than those of RE 4 Sb 3 14,15 and comparable to that of Yb 4 Bi 3−x Sb x around the same temperature. 40 In addition, it is worth mentioning that the break-out advantage of these materials would lie in their thermal conductivity which is expected to be very low based on the prevalent intricate bonding and atomic disorder at play in them.…”

“…Due to the inability to achieve single crystal growth via flux synthesis, we turned to the traditional solid-state synthesis approach by direct reaction which was also utilized for the reported Ca 3 RESb 3 , 16 RE 4 Sb 3 15 and Yb 4− x RE x Sb 3 14,15 phases. The procedures are typical of what was reported for Ca 3 RESb 3 and are as follows: stoichiometric amounts of the starting elements were loaded in a Nb tube inside a glove box followed by sealing it under argon gas atmosphere.…”

“…Due to the inability to achieve single crystal growth via flux synthesis, we turned to the traditional solid-state synthesis approach by direct reaction which was also utilized for the reported Ca 3 RESb 3 , 16 RE 4 Sb 3 15 and Yb 4−x RE x Sb 3 14,15 phases.…”

“…13 Substitution studies aimed to achieve a balanced electron count and with an attendant crystallographic disorder are fueled by the desire to achieve an optimal performing thermoelectric generator. One of such studies carried out is Yb 4−x RE x Sb 3 (RE = La and Sm) 14,15 and the recently reported Ca 4−x RE x Sb 3 (RE = La-Nd, Sm, Gd-Tm, the Lu) phases, 16 denoted hereafter as Ca 3 RESb 3 . The results in these studies clearly demonstrate the role-play of trivalent RE atom substitution on the cubic RE 4 Sb 3 [17][18][19] phases with the anti-Th 3 P 4 structure type in achieving a narrow bandgap semiconducting state due to the closed-shell electronic configuration achieved by all the elements.…”

Synthesis and Transport Properties of the Family of Zintl Phases Ca3RESb3 (RE = La–Nd, Sm, Gd–Tm, Lu): Exploring the Roles of Crystallographic Disorder and Core 4f Electrons for Enhancing Thermoelectric Performance

“…Since the electrical resistivities in these phases are expected to be relatively low, this could allow for an enhanced power factor PF. In Yb 4– x Sm x Sb 3 , one observes that the electrical resistivity is metallic in character, which is a pointer to the fact that these phases are heavily doped semiconductors, which is a key feature of high-performance TE materials. Such a feature is also expected in the title phases.…”