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 BaFe12O19/Bi2Te25Se0.5 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 BaFe12O19 hard-magnetic nanoparticles (NPs) is discovered, which can lower the carrier concentration of n-type Bi2Te2.5Se0.5 matrix by 16%, and increase the Seebeck coefficient by 16%. Meanwhile, BaFe12O19 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 n-type Bi2Te2.5Se0.5, and demonstrates magneto-trapped carrier effect as a universal strategy to enhance the electro-thermal conversion performance of TE materials with high carrier concentration.