Resonant States in the Electronic Structure of the High Performance Thermoelectrics AgPb$_{m}SbTe$_{2+m}$ ; The Role of Ag-Sb Microstructures

TL;DR

This paper investigates the electronic structure of AgPb$_{m}SbTe$_{2+m}$ thermoelectric materials, revealing resonant states and microstructural effects that contribute to their high thermoelectric efficiency at elevated temperatures.

Contribution

It provides new insights into how Ag-Sb microstructural arrangements influence electronic states and thermoelectric performance in these compounds.

Findings

Resonant states appear near the valence and conduction band edges.

Electronic structure is highly sensitive to Ag-Sb microstructural arrangements.

Large ZT values may be linked to specific atomic ordering patterns.

Abstract

Ab initio electronic structure calculations based on gradient corrected density functional theory were performed on a class of novel quaternary compounds AgPb$_{m}SbTe$_{2+m}$, which were found to be excellent high temperature thermoelctrics with large figure of merit ZT ~2.2 at 800K. We find that resonant states appear near the top of the valence and bottom of the conduction bands of bulk PbTe when Ag and Sb replace Pb. These states can be understood in terms of modified Te-Ag(Sb) bonds. Electronic structure near the gap depends sensitively on the microstructural arrangements of Ag-Sb atoms, suggesting that large ZT values may originate from the nature of these ordering arrangements.