skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Effect of extended strain fields on point defect phonon scattering in thermoelectric materials

Abstract

The design of thermoelectric materials often involves the integration of point defects (alloying) as a route to reduce the lattice thermal conductivity. Classically, the point defect scattering strength follows from simple considerations such as mass contrast and the presence of induced strain fields (e.g. radius contrast, coordination changes). While the mass contrast can be easily calculated, the associated strain fields induced by defect chemistry are not readily predicted and are poorly understood. In this work, we use classical and first principles calculations to provide insight into the strain field component of phonon scattering from isoelectronic point defects. Our results also integrate experimental measurements on bulk samples of SnSe and associated alloys with S, Te, Ge, Sr and Ba. These efforts highlight that the strength and extent of the resulting strain field depends strongly on defect chemistry. Strain fields can have a profound impact on the local structure. For example, in alloys containing Ba, the strain fields have significant spatial extent (1 nm in diameter) and produce large shifts in the atomic equilibrium positions (up to 0.5 A). Such chemical complexity suggests that computational assessment of point defects for thermal conductivity depression should be hindered. However, in this work, we presentmore » and verify several computational descriptors that correlate well with the experimentally measured strain fields. Furthermore, these descriptors are conceptually transparent and computationally inexpensive, allowing computation to provide a pivotal role in the screening of effective alloys. The further development of point defect engineering could complement or replace nanostructuring when optimizing the thermal conductivity, offering the benefits of thermodynamic stability, and providing more clearly defined defect chemistry.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1351592
Report Number(s):
NREL/JA-5K00-64949
Journal ID: ISSN 1463-9076
DOE Contract Number:
AC36-08GO28308
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Chemistry Chemical Physics. PCCP (Print); Journal Volume: 17; Journal Issue: 29
Country of Publication:
United States
Language:
English
Subject:
30 DIRECT ENERGY CONVERSION; fleet DNA; medium-duty; heavy-duty; drive cycle; data collection; data analysis; vocational database

Citation Formats

Ortiz, Brenden R., Peng, Haowei, Lopez, Armando, Parilla, Philip A., Lany, Stephan, and Toberer, Eric S. Effect of extended strain fields on point defect phonon scattering in thermoelectric materials. United States: N. p., 2015. Web. doi:10.1039/C5CP02174J.
Ortiz, Brenden R., Peng, Haowei, Lopez, Armando, Parilla, Philip A., Lany, Stephan, & Toberer, Eric S. Effect of extended strain fields on point defect phonon scattering in thermoelectric materials. United States. doi:10.1039/C5CP02174J.
Ortiz, Brenden R., Peng, Haowei, Lopez, Armando, Parilla, Philip A., Lany, Stephan, and Toberer, Eric S. Thu . "Effect of extended strain fields on point defect phonon scattering in thermoelectric materials". United States. doi:10.1039/C5CP02174J.
@article{osti_1351592,
title = {Effect of extended strain fields on point defect phonon scattering in thermoelectric materials},
author = {Ortiz, Brenden R. and Peng, Haowei and Lopez, Armando and Parilla, Philip A. and Lany, Stephan and Toberer, Eric S.},
abstractNote = {The design of thermoelectric materials often involves the integration of point defects (alloying) as a route to reduce the lattice thermal conductivity. Classically, the point defect scattering strength follows from simple considerations such as mass contrast and the presence of induced strain fields (e.g. radius contrast, coordination changes). While the mass contrast can be easily calculated, the associated strain fields induced by defect chemistry are not readily predicted and are poorly understood. In this work, we use classical and first principles calculations to provide insight into the strain field component of phonon scattering from isoelectronic point defects. Our results also integrate experimental measurements on bulk samples of SnSe and associated alloys with S, Te, Ge, Sr and Ba. These efforts highlight that the strength and extent of the resulting strain field depends strongly on defect chemistry. Strain fields can have a profound impact on the local structure. For example, in alloys containing Ba, the strain fields have significant spatial extent (1 nm in diameter) and produce large shifts in the atomic equilibrium positions (up to 0.5 A). Such chemical complexity suggests that computational assessment of point defects for thermal conductivity depression should be hindered. However, in this work, we present and verify several computational descriptors that correlate well with the experimentally measured strain fields. Furthermore, these descriptors are conceptually transparent and computationally inexpensive, allowing computation to provide a pivotal role in the screening of effective alloys. The further development of point defect engineering could complement or replace nanostructuring when optimizing the thermal conductivity, offering the benefits of thermodynamic stability, and providing more clearly defined defect chemistry.},
doi = {10.1039/C5CP02174J},
journal = {Physical Chemistry Chemical Physics. PCCP (Print)},
number = 29,
volume = 17,
place = {United States},
year = {Thu Jan 01 00:00:00 EST 2015},
month = {Thu Jan 01 00:00:00 EST 2015}
}