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Enhancing the Thermoelectric Properties of Germanium Antimony Tellurides by Substitution with Selenium in Compounds GenSb2(Te1-xSex)n+3 (0 ≤ x ≤ 0.5; n ≥ 7)

Rosenthal, Tobias and Urban, Philipp and Nimmrich, Kathleen and Schenk, Ludwig and de Boor, Johannes and Stiewe, Christian and Oeckler, Oliver (2014) Enhancing the Thermoelectric Properties of Germanium Antimony Tellurides by Substitution with Selenium in Compounds GenSb2(Te1-xSex)n+3 (0 ≤ x ≤ 0.5; n ≥ 7). Chemistry of Materials, 26 (8), pp. 2567-2578. ACS Publications. DOI: 10.1021/cm404115k ISSN 0897-4756

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Abstract

Quenched pseudocubic germanium antimony tellurides (GST compounds) exhibit promising thermoelectric properties. These are related to the nanostructures which can be influenced by varying the composition and the thermal treatment. The substitution of Te by Se in bulk samples of GenSb2Ten+3 with high thermoelectric figures of merit (ZT) is possible over a wide compositional range. This results in solid solution series GenSb2(Te1–xSex)n+3 with 0 < x < 0.75 for n ≥ 7. Se substitution reduces the average lateral extension of the defect layers in quenched samples. This is a consequence of the reduced mobility during the quenching process due to the lower cubic to trigonal phase transition temperatures of Se-substituted samples. Most pronounced for n = 7, Se doping increases the transition temperatures between the nanostructured (pseudo)cubic modification of quenched samples and their layered trigonal phase. This increases the temperature ranges in which the materials can be employed without altering their nanostructures and properties. When Se is introduced, the Seebeck coefficient increases and the thermal conductivity decreases. The ZT value of Ge7Sb2Te8Se2, for instance, increases up to 1.2 at 425 °C, which is 6 times higher than that of Ge7Sb2Te10. Similarly, the ZT value of Ge12Sb2(Te1–xSex)15 increases up to a factor of 2 for x = 0.2 at temperatures below 400 °C. The most promising thermoelectric properties (ZT = 1.2 at 425 °C for n = 7 and ZT = 1.1 at 350 °C for n = 12) are observed for x = 0.2 whereas higher Se substitution rates result in a less pronounced effect. The average structures were determined by powder as well as single crystal X-ray diffraction (SCXRD). The real structure of quenched GenSb2(Te1–xSex)n+3 (0 ≤ x ≤ 0.5; n ≥ 7) bulk material was investigated by high-resolution electron microscopy (HRTEM) with respect to the degree of substitution (x) and correlated with the resulting changes of the thermoelectric properties. The decrease of the lateral extension of the defect layers with increasing Se content as found by HRTEM and electron diffraction is confirmed by SCXRD data for Ge∼5Sb2(Te0.13Se0.87)∼8.

Item URL in elib:https://elib.dlr.de/92534/
Document Type:Article
Title:Enhancing the Thermoelectric Properties of Germanium Antimony Tellurides by Substitution with Selenium in Compounds GenSb2(Te1-xSex)n+3 (0 ≤ x ≤ 0.5; n ≥ 7)
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Rosenthal, TobiasDepartment of Chemistry, Ludwig Maximilian University Munich, Butenandtstrasse 5-13, 81377 Munich, GermanyUNSPECIFIED
Urban, PhilippLeipzig University, IMKM, Scharnhorststr. 20, 04275 Leipzig, GermanyUNSPECIFIED
Nimmrich, KathleenDepartment of Chemistry, Ludwig Maximilian University Munich, Butenandtstrasse 5-13, 81377 Munich, GermanyUNSPECIFIED
Schenk, LudwigDepartment of Chemistry, Ludwig Maximilian University Munich, Butenandtstrasse 5-13, 81377 Munich, GermanyUNSPECIFIED
de Boor, JohannesGerman Aerospace Center, Institute of Materials Research, Köln, GermanyUNSPECIFIED
Stiewe, ChristianGerman Aerospace Center, Institute of Materials Research, Köln, GermanyUNSPECIFIED
Oeckler, OliverLeipzig University, IMKM, Scharnhorststr. 20, 04275 Leipzig, GermanyUNSPECIFIED
Date:19 March 2014
Journal or Publication Title:Chemistry of Materials
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:26
DOI :10.1021/cm404115k
Page Range:pp. 2567-2578
Publisher:ACS Publications
ISSN:0897-4756
Status:Published
Keywords:electric properties, superconductors, semiconductors; germanium, Ge; antimony, Sb; tellurium, Te; selenium, Se; mechanical properties, thermal properties
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:propulsion systems
DLR - Research area:Aeronautics
DLR - Program:L ER - Engine Research
DLR - Research theme (Project):L - Turbine Technologies
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Research > Thermoelectric Materials and Systems
Deposited By: Zabrocki, Dr. Knud
Deposited On:01 Dec 2014 10:39
Last Modified:06 Sep 2019 15:19

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