Thermoelectric transport properties of Ni-, Pd-, and Pt- doped skutterudites with S-filling as charge compensation

Zhikang Tu,Xin Li,Jiong Yang,Xin Sun,Lili Xi,Ruoxi Li

doi:10.1063/1.5095820

Abstract

Unlike typical electronegative guest filled skutterudites, which are doped with electron donors at Sb sites to form thermodynamically stable compounds. In this study, substituting at Co sites with Ni, Pd, and Pt atoms instead of at the Sb sites was analyzed. The influence of Ni, Pd, and Pt on the electronic band structure of Ni-, Pd-, and Pt-doped skutterudites was thoroughly analyzed. The degree of band splitting caused by the doping elements was analyzed and shown to be correlated with the strength of anti-bonding between the doping elements and neighboring Sb atoms. The electronic structures in the conduction band minimum (CBM) of the S-filled skutterudites did not undergo a significant change when compared to those of the doped skutterudites. Therefore, the thermoelectric (TE) performance was optimized because of the reduction in the degree of energy band splitting due to the addition of elements ranging from Ni to Pt.

Highlights

Seebeck or Peltier effect, has been widely used in microelectronics, infrared detection and aerospace industry.1–3 The maximum efficiency of TE materials is characterized by the dimensionless figure of merit zT = S2σT/(κL + κe), where S, σ, T, κL, and κe are the Seebeck coefficient, electrical conductivity, absolute temperature, and the lattice and electronic contributions to the total thermal conductivity κ, respectively
The performance of TE materials improved considerably in the mid-1990s and there have been ongoing improvements since. They have benefited from the new concepts of quantum confinement, proposed by Hick and Dresselhaus,4 and the “phonon-glass electron-crystal” (PGEC) concept proposed by Slack
The covalent interaction provides a unique localized “cluster vibration”, which significantly reduces lattice thermal conductivity along with the point-defect caused by Te substitution for Sb atoms

Summary

Introduction

S-filled CoSb3 compounds, with Ni and Pd substituted for Co atoms, have been successfully prepared and investigated.6,7 the influence of dopant elements on the electronic structure and TE transport properties remains unknown. Since the dopant atoms are essential for electronegative guest filled skutterudites, it is necessary to study the effects of dopant atoms on electronic structures and electrical transport properties.

Results

Conclusion