CaltechAUTHORS
  A Caltech Library Service

Nanostructures in Te/Sb/Ge/Ag (TAGS) Thermoelectric Materials Induced by Phase Transitions Associated with Vacancy Ordering

Schröder, Thorsten and Rosenthal, Tobias and Giesbrecht, Nadja and Nentwig, Markus and Maier, Stefan and Wang, Heng and Snyder, G. Jeffrey and Oeckler, Oliver (2014) Nanostructures in Te/Sb/Ge/Ag (TAGS) Thermoelectric Materials Induced by Phase Transitions Associated with Vacancy Ordering. Inorganic Chemistry, 53 (14). pp. 7722-7729. ISSN 0020-1669. https://resolver.caltech.edu/CaltechAUTHORS:20140821-091004857

[img]
Preview
PDF (Supporting Information) - Supplemental Material
See Usage Policy.

703Kb
[img] Crystallographic Info File (CIF) (Supporting Information) - Supplemental Material
See Usage Policy.

10Kb
[img] Crystallographic Info File (CIF) (Supporting Information) - Supplemental Material
See Usage Policy.

10Kb
[img] Crystallographic Info File (CIF) (Supporting Information) - Supplemental Material
See Usage Policy.

8Kb

Use this Persistent URL to link to this item: https://resolver.caltech.edu/CaltechAUTHORS:20140821-091004857

Abstract

Te/Sb/Ge/Ag (TAGS) materials with rather high concentrations of cation vacancies exhibit improved thermoelectric properties as compared to corresponding conventional TAGS (with constant Ag/Sb ratio of 1) due to a significant reduction of the lattice thermal conductivity. There are different vacancy ordering possibilities depending on the vacancy concentration and the history of heat treatment of the samples. In contrast to the average α-GeTe-type structure of TAGS materials with cation vacancy concentrations <3%, quenched compounds like Ge_(0.53)Ag_(0.13)Sb_(0.27)□_(0.07)Te_1 and Ge_(0.61)Ag_(0.11)Sb_(0.22)□_(0.06)Te_1 exhibit “parquet-like” multidomain nanostructures with finite intersecting vacancy layers. These are perpendicular to the pseudocubic 111 directions but not equidistantly spaced, comparable to the nanostructures of compounds (GeTe)_nSb_2Te_3. Upon heating, the nanostructures transform into long-periodically ordered trigonal phases with parallel van der Waals gaps. These phases are slightly affected by stacking disorder but distinctly different from the α-GeTe-type structure reported for conventional TAGS materials. Deviations from this structure type are evident only from HRTEM images along certain directions or very weak intensities in diffraction patterns. At temperatures above 400 °C, a rock-salt-type high-temperature phase with statistically disordered cation vacancies is formed. Upon cooling, the long-periodically trigonal phases are reformed at the same temperature. Quenched nanostructured Ge_(0.53)Ag_(0.13)Sb_(0.27)□_(0.07)Te_1 and Ge_(0.61)Ag_(0.11)Sb_(0.22)□_(0.06)Te_1 exhibit ZT values as high as 1.3 and 0.8, respectively, at 160 °C, which is far below the phase transition temperatures. After heat treatment, i.e., without pronounced nanostructure and when only reversible phase transitions occur, the ZT values of Ge_(0.53)Ag_(0.13)Sb_(0.27)□_(0.07)Te_1 and Ge_(0.61)Ag_(0.11)Sb_(0.22)□_(0.06)Te_1 with extended van der Waals gaps amount to 1.6 at 360 °C and 1.4 at 410 °C, respectively, which is at the top end of the range of high-performance TAGS materials.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/ic5010243DOIArticle
http://pubs.acs.org/doi/abs/10.1021/ic5010243PublisherArticle
http://pubs.acs.org/doi/suppl/10.1021/ic5010243PublisherSuupporting Information
ORCID:
AuthorORCID
Maier, Stefan0000-0002-2210-6290
Snyder, G. Jeffrey0000-0003-1414-8682
Additional Information:© 2014 American Chemical Society. Received: May 5, 2014; Published: July 7, 2014. We thank Thomas Miller and Christian Minke (LMU Munich) for the temperature-dependent powder diffraction experiments and for SEM-EDX analyses, respectively. We are grateful to Prof. Dr. W. Schnick (LMU Munich) for the generous support of this work. Furthermore, we thank Fivos Drymiotis (California Institute of Technology) for help with the thermoelectric measurements. This investigation was funded by the Deutsche Forschungsgemeinschaft (Grant OE530/1−2) and the Studienstiftung des deutschen Volkes (scholarship for T.S.).
Funders:
Funding AgencyGrant Number
Deutsche Forschungsgemeinschaft (DFG)OE530/1−2
Studienstiftung des deutschen VolkesUNSPECIFIED
Issue or Number:14
Record Number:CaltechAUTHORS:20140821-091004857
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140821-091004857
Official Citation:Nanostructures in Te/Sb/Ge/Ag (TAGS) Thermoelectric Materials Induced by Phase Transitions Associated with Vacancy Ordering Thorsten Schröder, Tobias Rosenthal, Nadja Giesbrecht, Markus Nentwig, Stefan Maier, Heng Wang, G. Jeffrey Snyder, and Oliver Oeckler Inorganic Chemistry 2014 53 (14), 7722-7729
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:48764
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:21 Aug 2014 19:52
Last Modified:09 Mar 2020 13:19

Repository Staff Only: item control page