一步法制备重费米子 YbAl_(3)热电材料及其性能提升

Heavy-Fermion YbAl_(3) Materials:One-step Synthesis and Enhanced Thermoelectric Performance

材料的微观结构对其物理性能调控起着至关重要的作用。本研究以Yb和Al单质为原料,采用放电等离子烧结工艺通过一步法快速合成YbAl_(3)材料。显微结构表明,快速制备的YbAl_(3)材料内部含有大量微米尺度晶粒、纳米晶粒、纳米非晶带和多种原子尺度位错等丰富的多尺度微结构,这些多尺度微结构可以同时增强YbAl_(3)材料的电子和声子散射,进而同时降低其晶格热导率(47%)和电子热导率(27%),使得总热导率降低至13.4 W·K^(–1)·m^(–1),YbAl_(3)材料的最大ZT可达0.35。该研究表明,通过一步法放电等离子烧结工艺可以快速合成具有多尺度微结构的高热电性能YbAl_(3)块体材料。

Microstructure plays a key role in tuning physical properties of materials.Here YbAl_(3) materials with high figure of merit ZT of 0.35 at 300 K was directly synthesized with Yb and Al pure powders through one-step spark plasma sintering process in 10 min.The excellent thermoelectric performance is attributed to the simultaneous reduction in the lattice thermal conductivity by 47%and electronic thermal conductivity by 27%at 300 K.The remarkable decrease in the electronic thermal conductivity is ascribed to the enhanced scattering of electrons by nanocrystals with 5–20 nm in diameter,strip-like non-crystal with several nanometers in width and various atomic-scale distortions.The substantial decline in the lattice thermal conductivity originates from the enhanced scattering of phonons due to multi-scale microstructures spanning from nanoscale to mesoscale.This work demonstrates that one-step spark plasma sintering process is an efficient strategy to rapidly synthesize YbAl_(3) materials with multi-scale microstructures and enhanced thermoelectric performance.