Thermoelectric properties of Ag2Sb2Ge46 − xDyxTe50 alloys with high power factor. Issue 12 (19th September 2013)

• Record Type: Journal Article
• Authors: Levin, E. M.; Hanus, R.; Hanson, M.; Straszheim, W. E.; Schmidt‐Rohr, K.
• Is Part Of: Physica status solidi. Volume 210:Issue 12(2013:Dec.)
• Page Start: 2628
• Page End: 2637
• Publication Date: 2013-09-19
• Subjects: Solid state physics -- Periodicals; Solids -- Industrial applications -- Periodicals; 530.41
• DOI: 10.1002/pssa.201330217
• Languages: English
• ISSNs: 1862-6300

Abstract

<abstract abstract-type="main" xml:lang="en"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="pssa201330217-sec-0001" sec-type="section"> <p>A comprehensive study of GeTe‐based materials where Ge is replaced by 2 at.% Ag, 2 at.% Sb, and additionally by 1 or 2 at.% Dy (Ag<sub>2</sub>Sb<sub>2</sub>Ge<sub>46 − <italic>x</italic></sub>Dy<sub><italic>x</italic></sub>Te<sub>50</sub> alloys) has been conducted using Seebeck coefficient, electrical resistivity, and thermal conductivity measurements in the temperature range of 300–750 K, and X‐ray diffraction (XRD) and <sup>125</sup>Te NMR at 300 K. According to our data, at ∼720 K, GeTe, a self‐doping degenerate semiconductor, exhibits the highest known power factor (PF) among tellurides, 42 μW cm<sup>−1</sup> K<sup>−2</sup>, but due to high thermal conductivity, the thermoelectric figure of merit, <italic>ZT</italic>, is relatively low, ∼0.8. Replacement of Ge in GeTe by [Ag + Sb] and Dy enhances the Seebeck coefficient and produces a small increase in carrier concentration deduced from <sup>125</sup>Te NMR spin–lattice relaxation. The PF of Ag<sub>2</sub>Sb<sub>2</sub>Ge<sub>45</sub>Dy<sub>1</sub>Te<sub>50</sub> at ∼720 K is found to be still high, 40 μW cm<sup>−1</sup> K<sup>−2</sup>, and due to a reduction in thermal conductivity, <italic>ZT</italic> reaches 1.2. Our data show that relatively high <italic>ZT</italic> values in tellurides can be obtained primarily due to high PF while thermal conductivity is moderate. The enhancement of the Seebeck coefficient observed in Ag<sub>2</sub>Sb<sub>2</sub>Ge<sub>46 − <italic>x</italic></sub>Dy<sub><italic>x</italic></sub>Te<sub>50</sub> alloys can be attributed to energy filtering due potential barriers formed by [Ag + Sb] and rare‐earth Dy atoms.</p> </sec> </abstract>