摘要
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.
在同一尺度协同调控非笼状结构热电材料载流子输运和声子输运面临巨大挑战.本文设计并制备了BaFe_(12)O_(19)/Bi_(2)Te_(2.5)Se_(0.5)热电磁纳米复合材料,实现了纳米尺度协同调控电热输运性能.研究表明,BaFe_(12)O_(19)硬磁纳米粒子产生的磁束缚载流子效应导致载流子浓度降低16%,Seebeck系数提高16%.同时,BaFe_(12)O_(19)纳米粒子作为声子散射中心,增强了声子散射,使热导率降低12%.热电磁纳米复合材料在300–450 K温度范围内的平均ZT值提高了25%,室温附近的制冷温差提高了65%.本研究极大地拓宽了n型Bi_(2)Te_(2.5)Se_(0.5)的商业化应用潜力,证明了磁束缚载流子效应是一种提升高载流子浓度热电材料电热转换性能的普适方法.
基金
the National Natural Science Foundation of China(11834012,51620105014,91963207,91963122 and 51902237)
the National Key Research and Development Program of China(2018YFB0703603,2019YFA0704900 and SQ2018YFE010905)
Foshan Xianhu Laboratory of Advanced Energy Science and Technology Guangdong Laboratory(XHT2020-004)。
