Synthesis and Electronic Properties of Thermoelectric and Magnetic Nanoparticle Composite Materials

Abstract

Application of a magnetic field greatly enhances the thermoelectric efficiency of bismuth-antimony (Bi-Sb) alloys. We synthesized a hybrid of Bi-Sb alloy and magnetic nanoparticles, expecting improvement of the thermoelectric performance due to the magnetic field generated by the nanoparticles. Powder x-ray diffraction and magnetic measurements of the synthesized hybrid Bi 0.88 Sb 0.12 (FeSb) 0.05 sample indicated that the ferromagnetic FeSb nanoparticles, with a size of about 30 nm, were distributed in the main phase of the Bi-Sb alloy. The FeSb nanoparticles act as soft ferromagnets in the diamagnetic host Bi-Sb alloy. The electrical resistivity q of the host Bi 0.88 Sb 0.12 sample decreased concomitantly with decreasing temperature, showing a shoulder at 80 K. In contrast, q for the hybrid sample was enhanced below 100 K because of carrier scattering by the nanoparticles. The temperature dependence of the Seebeck coefficient S was also altered by the nanoparticle addition. In contrast, the addition of magnetic nanoparticles only slightly influenced the thermal conductivity j. These results indicate that the addition of magnetic nanoparticles to thermoelectric materials modulates the electronic structures but does not influence the lattice system.

Fine-Grained Bi–Sb Ribbons with Modulation-Doped FeSb Nanoparticles for High-Temperature Cryogenic Applications

“…Here, α for all samples first increases slowly to a maximum at ∼130−150 K and then shows a sharp drop as the temperature is decreased. Such variation in the Seebeck coefficient, as observed in the present case, had also been reported by several groups in singlecrystal 53 and mechanically alloyed polycrystalline 26,30 systems. Furthermore, it is worth noting that the incorporation of FeSb NPs into the Bi 1−x Sb x matrix does not change the carrier-type present in hybrid samples.…”

“…Here, α for all samples first increases slowly to a maximum at ∼130−150 K and then shows a sharp drop as the temperature is decreased. Such variation in the Seebeck coefficient, as observed in the present case, had also been reported by several groups in singlecrystal 53 and mechanically alloyed polycrystalline 26,30 16 As shown in Figure 5c, the calculated power factor, PF, of all of the prepared samples shows notable improvement with decreasing temperature, which maximizes at ∼70−100 K and drops sharply at further low temperatures. For hybrid samples, PF exhibits an ∼50% gain over a broad temperature range, with their maxima pushed to higher temperatures.…”

“…This shifted the focus in favor of polycrystalline Bi 1– x Sb x alloys . But the problem with polycrystalline Bi 1– x Sb x alloy is its low ZT value, which, until now, has not been satisfactorily enhanced by employing several physical approaches such as mechanical alloying, , spark plasma sintering, , quenching–annealing, − etc. In the Bi–Sb phase diagram, the temperature gap between liquidus–solidus spindle-shaped regions causes significant phase segregation under normal cooling conditions, preventing the formation of a homogeneous alloy ingot.…”

Magnetism Modulation for Cryogenic Thermoelectric Enhancements in Fe3O4 Nanoparticle-Incorporated Bi0.85Sb0.15 Nanocomposites

“…The interaction between the electrons and magnetic moments of nanoparticles leads to the thermo-electro-magnetic coupling effects, such as the magneto-trapped carrier effect, , carrier multiple scattering effect, and magnon-drag thermopower effect . Since Bi–Sb alloys have a small effective mass and very high carrier mobility, their TE properties may be susceptible to magnetic nanoparticles due to the generated Lorentz force. , Hitherto, there are a few studies on the role of magnetic nanoparticles in the TE properties of Bi–Sb materials. , …”

Thermoelectric performance of polyparaphenylene/Li0·5Ni0·5Fe2O4 nanocomposites

“…Composite materials consisting of inorganic TE nanostructures and polymer have much better TE properties than pure polymer, as the composite materials could inherit the properties of both the polymer and the inorganic nanostructures and even have a synergistic effect. [20][21][22][23][24][25] Future efforts targeted at compositional optimisation and variation of quantum confined inorganic may lead to even high ZTs.…”