Thermoelectric properties of hexagonal WN6 from first-principles calculations

Xueliang Zhu 1

Pengfei Liu 2,3

Hao Gao 8

Guofeng Xie 4, 5, Email

Baotian Wang 2, 3, 6, 7, Email

1 School of Physics and Optoelectronics, Xiangtan University, Hunan 411105, PChina.

2 Institute of High Energy Physics, Chinese Academy of Sciences (CAS), Beijing 100049, China.

3 Dongguan Neutron Science Center, Dongguan 523803, China.

4 School of Materials Science and Engineering, Hunan University of Science and Technology, 411201 Xiangtan, China.

5 Hunan Provincial Key Lab of Advanced Materials for New Energy Storage and Conversion, Xiangtan, China.

6 Institute of Applied Physics and Computational Mathematics, Beijing 100088, China.

7 Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China.

8 National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.

Abstract

Recent research demonstrated high thermoelectric figure of merit in CrN, implying that the transition metal nitrides could be promising thermoelectric materials. Herein, we investigate the thermoelectric properties of a newly predicted superhard material WN6 by using first-principles calculations and Boltzmann transport theory. Results indicate that WN6 has a small band gap of 0.76 eV, a relatively low lattice thermal conductivity of around 10.7 W/mk at 700 K, and a large Seeback coefficient of 1330 μV/K at 300 K. Its low lattice thermal conductivity and large Seeback coefficient lead to an excellent thermoelectric response, with the maximum thermoelectric figure of merit being 0.78 for n-type. The mode Grüneisen parameters and phonon mean free path are exhibited to analyze the anharmonic properties and the size effects. These results shed light on the thermoelectric performance of WN6.

Thermoelectric properties of hexagonal WN6 from first-principles calculations