Enhanced Thermoelectric Performance in Ternary Skutterudite Co(Ge0.5Te0.5)3via Band Engineering
Journal
Inorganic Chemistry
Journal Volume
61
Journal Issue
10
Pages
4442-4452
Date Issued
2022
Author(s)
Abstract
We report the phase evolution and thermoelectric properties of a series of Co(Ge0.5Te0.5)3-xSbx (x = 0-0.20) compositions synthesized by mechanical alloying. Pristine ternary Co(Ge0.5Te0.5)3 skutterudite crystallizes in the rhombohedral symmetry (R3¯), and Sb doping induces a structural transition to the cubic phase (ideal skutterudite, Im3¯). The Sb substitution increases the carrier concentration while maintaining a high thermopower even at higher doping levels owing to an increased effective mass. The exceptional electronic properties exhibited by Co(Ge0.5Te0.5)3 upon doping are attributed to the carrier transport from both the primary and secondary conduction bands, as shown by theoretical calculations. The enhanced electrical conductivity and high thermopower increase the power factor by more than 20 times. Because the dominant phonon propagation modes in binary skutterudites are associated with the vibrations of pnictogen rings, twisting the latter through the isoelectronic replacement of Sb4 rings with Ge2Te2 ones, as done in this study, can effectively reduce the thermal conductivity. This leads to an increase in the dimensionless figure-of-merit (zT) by a factor of 30, reaching 0.65 at 723 K for Co(Ge0.5Te0.5)2.9Sb0.1. © 2022 American Chemical Society.
Other Subjects
Antimony;Carrier concentration;Electronic properties;Mechanical alloying;Skutterudites;Thermal conductivity;Band engineering;Cubic phase;Phase evolutions;Rhombohedral symmetry;Sb doping;Structural transitions;Synthesised;Ternary skutterudite;Thermoelectric performance;Thermoelectric properties;Thermoelectric power;article;calculation;conformational transition;crystallization;doping;electric conductivity;phonon;thermal conductivity;vibration
Type
journal article