|
Vol.60, No.11, 858 ~ 865, 2022
|
| Title |
| Effects of V Alloying on Thermoelectric Properties of NbFeSb Half-Heusler Materials Codoped with Ti, Zr, and Sn |
| Sung-jae Joo , Jeongin Jang , Ji-hee Son , Bong-seo Kim , Bok-ki Min |
|
|
|
| Abstract |
| NbFeSb-based alloys are promising p-type half-Heusler materials with excellent thermoelectric performance, thermal stability, and naturally abundant constituent elements. Alloying and doping are powerful techniques for enhancing the thermoelectric properties of half-Heusler materials. This study experimentally investigated the effects of V alloying in NbFeSb codoped with Ti, Zr, and Sn. As the V content increases, the electrical conductivity of Nb0.8-xVxTi0.15Zr0.05FeSb0.98Sn0.02 (x = 0, 0.05, 0.1, 0.2, and 0.3) decreases monotonically because of a simultaneous reduction in carrier concentration and mobility, reducing the power factor up to -39% from 4.13 (x = 0) to 2.52 mW m-1K-2 (x = 0.3) at 298 K. Moreover, the lattice thermal conductivity decreases with increasing x by as much as -40% at the maximum V content of x = 0.3, demonstrating that V addition considerably enhances phonon scattering even in the presence of substitutional dopants Ti, Zr, and Sn. The differences in the mass and size of V and Nb atoms cause a substantial decrease in lattice thermal conductivity. According to our study, the addition of a small V content to Hf-free NbFeSbbased alloys can improve their thermoelectric properties, and a maximum dimensionless figure of merit zT of 0.89 was obtained in Nb0.75V0.05Ti0.15Zr0.05Sn0.98Sb0.02 at 973 K.
(Received 19 July, 2022; Accepted 18 August, 2022) |
|
|
| Key Words |
| thermoelectric properties, half-Heusler, NbFeSb, V, thermal conductivity |
|
|
 |
|
