| About this Abstract |
| Meeting |
Materials Science & Technology 2020
|
| Symposium
|
Controlled Synthesis, Processing, and Applications of Structural and Functional Nanomaterials
|
| Presentation Title |
Control Over Structure and Chemistry Across Multiple Lengthscales in Fe-Si-Ge-Based Thermoelectrics |
| Author(s) |
Naiming Liu, Mona Zebarjadi, Jerrold A. Floro |
| On-Site Speaker (Planned) |
Jerrold A. Floro |
| Abstract Scope |
We synthesized FeSi<sub>2</sub> – SiGe nanocomposites via React/Transform Spark Plasma Sintering, in which eutectoid decomposition, Ge alloying, doping and sintering efficiently occurred in a single process. This produced hierarchical structuring with a percolated DC network coexisting with discrete nanoscale inclusions, embedded in the FeSi<sub>2</sub> matrix. This partially decouples thermal and electrical transport. Alloy chemistry was crucial to improving properties: Ge increases phonon scattering while reducing the DC bandgap; selective doping of both phases provides the requisite carrier concentration, while minor additions of Cu and Sb accelerate eutectoid decomposition, and reduce sintering temperatures, respectively. Hall measurements show that the electron mobilities are 25 times higher than similar materials produced using typical powder processing. The maximum thermoelectric figure of merit ZT of ~0.67 at 973K is a record for this system. Since the nanocomposite is primarily Fe and Si, it is non-toxic, eco-friendly, and the components are relatively abundant and inexpensive. |