Magneto-enhanced electro-thermal conversion performance

Abstract

Synergistically regulating carrier and phonon transport on the nanoscale is extremely difficult for all thermoelectric (TE) materials without cage structures. Herein BaFe 12 O 19 /Bi 2 Te 2.5 Se 0.5 thermoelectromagnetic nanocomposites are designed and synthesized as a benchmarking example to simultaneously tailor the transport properties on the nanoscale. A magneto-trapped carrier effect induced by BaFe 12 O 19 hard-magnetic nanoparticles (NPs) is discovered, which can lower the carrier concentration of n-type Bi 2 Te 2.5 Se 0.5 matrix by 16%, and increase the Seebeck coefficient by 16%. Meanwhile, BaFe 12 O 19 NPs provide phonon scattering centers and reduce the thermal conductivity by 12%. As a result, the ZT value of the nanocomposites is enhanced by more than 25% in the range of 300-450 K, and the cooling temperature difference increases by 65% near room temperature. This work greatly broadens the commercial application potential of ntype Bi 2 Te 2.5 Se 0.5 , and demonstrates magneto-trapped carrier effect as a universal strategy to enhance the electro-thermal conversion performance of TE materials with high carrier concentration.

Magnetically Enhanced Thermoelectric Performance of Ti0.75NiSb+x mol % Fe (x = 0–5) Nanocomposites

“…Similar case has been found in other magnetic nanocomposites. [28][29][30][31][32][33]37 The rough interfaces and boundaries induced by Fe nanoparticles are favorable for the enhancement of phonon scattering.…”

“…Therefore, the ferromagnetic Fe nanoparticles form a built-in magnetic field in Ti 0.75 NiSb, which affects the carriers involved in the transport, as shown in Figure 4e. Spherical Fe nanoparticles with radius r x can generate a magnetic field of intensity B for carriers at a distance l from the spherical surface, which can be expressed as follows 29 = + B Jr l r 2 3( )…”

“…For the increase in carrier concentration, some works attribute it to charge transfer. 32,33 For the reduction of carrier concentration, some works attribute it to the generation of a magneto-trapped carrier effect, 28,29,34 and some works attribute it to the formation of a p−n junction. 30,31 Unlike previous work, both Fe and To further analyze the effect of magnetic Fe nanoparticles on the electronic transport of Ti 0.75 NiSb, Figure 9a shows the Pisarenko line at 300 K for Ti 0.75 NiSb based on a single parabolic band (SPB) model with acoustic phonon scattering (scattering factor r = −0.5) with an estimated density of states effective mass m* of 5.99 m 0 .…”

Realizing High‐Performance BiSbTe Magnetic Flexible Films via Acceleration Movement and Hopping Migration of Carriers

“…[ 13 ] Unfortunately, such a strategy shows little effect on the conventional TE semiconductors. [ 14,15 ] Recently, it was reported that the magnetism incorporated into various bulk TE materials can significantly enhance the electrical and thermal transport properties due to the induced thermo‐electro‐magnetic coupling effects such as electron repository effect, [ 16 ] carrier multiple scattering effect, [ 17 ] superparamagnetism‐enhanced Seebeck effect, [ 18–20 ] magneto‐trapped carrier effect, [ 21 ] magnetoresistance‐enhanced TE effect, [ 22 ] magnetic‐field‐enhanced TE effect, [ 12,13 ] and (para)magnon‐drag Seebeck effect. [ 23 ] These coupling effects induced by magnetic nanoparticles provide unconventional pathways to simultaneously regulate electrical and thermal transport properties on the same scale for all TE materials regardless of the crystal structure.…”

“…Thermoelectric (TE) films are key materials in developing emergent applications such as wearable TE power generation, biaxial thermal management, and full solid-state refrigeration. To maximize the electro-thermal conversion and reachability, the TE films should simultaneously possess excellent TE performance magneto-trapped carrier effect, [21] magnetoresistance-enhanced TE effect, [22] magnetic-field-enhanced TE effect, [12,13] and (para) magnon-drag Seebeck effect. [23] These coupling effects induced by magnetic nanoparticles provide unconventional pathways to simultaneously regulate electrical and thermal transport properties on the same scale for all TE materials regardless of the crystal structure.…”