Gallium composition dependence of crystallographic and thermoelectric properties in polycrystalline type-I Ba8GaxSi46−x (nominal x=14–18) clathrates prepared by combining arc melting and spark plasma sintering methods

Si‐based Clathrates with Partial Substitution by Zn and Ga: K8Zn3.5Si42.5, Rb7.9Zn3.6Si42.4, and Cs8–xGa8–ySi38+y

“…The total values are 2–4 times higher than that observed for Ba 8 Zn 7 Si 39 18. The Seebeck coefficient of compound 3 at room temperature is 160 μV · K –1 , and thus it is approximately three times larger than that observed for Ba 8 Ga x Si 46– x ,9 but two times smaller than that observed for A 8 Al 8 Si 38 10. All clathrates 1 – 3 show small figures of merit (see Supporting Information, Figure S5).…”

“…The highest ZT values for intermetallic clathrates are observed for Ba 8 Ga 16 Sn 30 6 ( ZT = 1.45 at 500 K) and Ba 8 Ga 16 Ge 30 7 ( ZT = 1.35 at 900 K). Some of the last reported values include Si‐based clathrates and are 0.4 at 900 K for Ba 8 Al 16 Si 30 8 and 0.55 at 900 K for Ba 8 Ga 14.51 Si 31.49 9. The recently reported clathrates A 8 Al 8 Si 38 ( A = K, Rb, Cs)10 show low ZT values due to the high resistivity of the samples, however, the Seebeck coefficient of more than 200 μV · K –1 at room temperature is significantly higher than those reported for Ba‐containing Si‐based clathrates (≈50 μV · K –1 Ba 8 Al 16 Si 30 8 for and ≈55 μV · K –1 for Ba 8 Ga 14.51 Si 31.49 9).…”

“…Some of the last reported values include Si‐based clathrates and are 0.4 at 900 K for Ba 8 Al 16 Si 30 8 and 0.55 at 900 K for Ba 8 Ga 14.51 Si 31.49 9. The recently reported clathrates A 8 Al 8 Si 38 ( A = K, Rb, Cs)10 show low ZT values due to the high resistivity of the samples, however, the Seebeck coefficient of more than 200 μV · K –1 at room temperature is significantly higher than those reported for Ba‐containing Si‐based clathrates (≈50 μV · K –1 Ba 8 Al 16 Si 30 8 for and ≈55 μV · K –1 for Ba 8 Ga 14.51 Si 31.49 9). Changing the carrier concentration by tuning the electronic structure through element substitution could increase the Figure of merit for A 8 Al 8 Si 38 clathrates significantly.…”

Thermal conductivity in intermetallic clathrates: A first-principles perspective

“…It shall also be noted that the experimentally determined lattice parameters and compositions can vary markedly depending on the measurement technique. 11,48,51 Both functionals overestimate the lattice parameter compared to experiment, with PBE always giving the higher estimate (Table I and Fig. 2).…”

Ultra‐Fast One‐Step Fabrication of Cu2Se Thermoelectric Legs With Ni–Al Electrodes by Plasma‐Activated Reactive Sintering Technique

“…Currently, the fabrication of TE devices is an assembly process from materials to a module. TE materials are synthesized in advance by one of the techniques appropriate for that particular class of materials which may include melting and solidification methods, solid state reaction, levitation melting, mechanical alloying, melt spinning, arc melting, and others. Since not every synthesis process results in a well‐densified material, the grown ingots or pellets are ground into a powder and either hot‐pressed (HP) or spark plasma sintered (SPS) to the near theoretical density of the material.…”