Large mass field fluctuation and lattice anharmonicity effects promote thermoelectric and mechanical performances in NbFeSb half-Heusler alloys via Ti/Zr/Hf stepwise doping

Abstract

Thermoelectric materials require not only high performance to maximize the energy conversion efficiency but also good mechanical properties to guarantee machinability and reliable operation. In this work, multi-element doping NbFeSb-based...

The Substitution of Rare-Earth Gd in BaScCuTe3 Realizing the Band Degeneracy and the Point-Defect Scattering toward Enhanced Thermoelectric Performance

“…When x = 0.03, this parameter for the doped samples reaches the lowest value of 0.48 W/m·K, which approaches the amorphous limit of lattice thermal conductivity (0.395 W/m·K) of BaScCuTe 3 estimated from the Cahill model. To further understand the origin of ultralow lattice thermal conductivity, sound velocity for BaScCuTe 3 and some state-of-art thermoelectric materials are provided for comparison (Table and Figure (c)). − In addition to the well-known half-Heusler alloy and skutterudite, other high-performance thermoelectric compounds all show low sound velocity and low lattice thermal conductivity, due to weak chemical bonding and the small phonon mean free path …”

High-entropy materials for thermoelectric applications: towards performance and reliability

“…In particular, Nb 0.82 Ti 0.06 Zr 0.06 Hf 0.06 FeSb exhibited the highest PF value of 40.3 μW cm −1 K −2 at 973 K and achieved the lowest lattice k of 3.6 W m −1 K −1 at 973 K, which was approximately half that of pristine NbFeSb. Consequently, Nb 0.82 Ti 0.06 Zr 0.06 Hf 0.06 FeSb achieved a high ZT value of 0.74 at 973 K and maintained an average ZT of 0.45 ranging from 333 K to 973 K. 174 Zhang et al have also applied the entropy-driven concept on a Hf-free HH compound and found a k of 3.14 W m −1 K −1 at 870 K and a very low k l of 0.48 W m −1 K −1 at 870 K of Ti 0.57 Zr 0.4 Al 0.02 Ta 0.01 NiSn 0.98 Sb 0.02 , which represents an 82.3% decrease compared to that of pristine TiNiSn. As a result, ZT has risen from 0.67 for TiNiSn to ∼1.4 for Ti 0.57 Zr 0.4 Al 0.02 Ta 0.01 NiSn 0.98 Sb 0.02 at 870 K, resulting in an increase of almost 108% that was accomplished through entropy engineering.…”

“…6B 3 ), nearly five times that of Ti 2 FeNiSb 2 . 173 Tan et al 174 have designed multi-element-doped NbFeSb-based alloys by introducing Ti, Zr, and Hf atoms into the Nb sites through a stepwise doping process. This doping resulted in an increase in the n-type hole-carrier concentration and an enhancement in electrical transport properties.…”