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A New Material with a Composite Crystal Structure Causing Ultralow Thermal Conductivity and Outstanding Thermoelectric Properties : Tl 2 Ag 12 Te 7+δ

Shi, Yixuan ; Assoud, Abdeljalil ; Ponou, Simeon LU ; Lidin, Sven LU and Kleinke, Holger (2018) In Journal of the American Chemical Society 140(27). p.8578-8585
Abstract


A new state-of-the-art thermoelectric material, Tl
2
Ag
12
Te
7+δ
, which possesses an extremely low thermal conductivity of about 0.25 W m
-1
K
-1
and a high figure-of-merit of up to 1.1 at 525 K, was obtained using a conventional solid-state reaction approach. Its subcell is a variant of the Zr
... (More)


A new state-of-the-art thermoelectric material, Tl
2
Ag
12
Te
7+δ
, which possesses an extremely low thermal conductivity of about 0.25 W m
-1
K
-1
and a high figure-of-merit of up to 1.1 at 525 K, was obtained using a conventional solid-state reaction approach. Its subcell is a variant of the Zr
2
Fe
12
P
7
type, but ultimately its structure was refined as a composite structure of a Tl
2
Ag
12
Te
6
framework and a linear Te atom chain running along the c axis. The super-space group of the framework was determined to be P6
3
(00γ)s with a = b = 11.438(1) Å, c = 4.6256(5) Å, and that of the Te chain substructure has the same a and b axes, but c = 3.212(1) Å, space group P6(00γ)s. The modulation leads to the formation of Te
2
and Te
3
fragments in this chain and a refined formula of Tl
2
Ag
11.5
Te
7.4
. The structure consists of a complex network of three-dimensionally connected AgTe
4
tetrahedra forming channels filled with the Tl atoms. The electronic structures of four different models comprising different Te chains, Tl
2
Ag
12
Te
7
, Tl
2
Ag
12
Te
7.33
, and 2× Tl
2
Ag
12
Te
7.5
, were computed using the WIEN2k package. Depending on the Te content within the chain, the models are either semiconducting or metallic. Physical property measurements revealed semiconducting properties, with an ultralow thermal conductivity, and excellent thermoelectric properties at elevated temperatures.

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; ; ; and
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publishing date
type
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publication status
published
subject
in
Journal of the American Chemical Society
volume
140
issue
27
pages
8 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • scopus:85048829628
ISSN
0002-7863
DOI
10.1021/jacs.8b04639
language
English
LU publication?
yes
id
044b8a84-b84a-41a2-a5e5-8d895bee70ab
date added to LUP
2019-04-08 14:53:22
date last changed
2020-12-29 01:47:46
@article{044b8a84-b84a-41a2-a5e5-8d895bee70ab,
  abstract     = {<p><br>
                            A new state-of-the-art thermoelectric material, Tl<br>
                            <sub>2</sub><br>
                            Ag<br>
                            <sub>12</sub><br>
                            Te<br>
                            <sub>7+δ</sub><br>
                            , which possesses an extremely low thermal conductivity of about 0.25 W m<br>
                            <sup>-1</sup><br>
                             K<br>
                            <sup>-1</sup><br>
                             and a high figure-of-merit of up to 1.1 at 525 K, was obtained using a conventional solid-state reaction approach. Its subcell is a variant of the Zr<br>
                            <sub>2</sub><br>
                            Fe<br>
                            <sub>12</sub><br>
                            P<br>
                            <sub>7</sub><br>
                             type, but ultimately its structure was refined as a composite structure of a Tl<br>
                            <sub>2</sub><br>
                            Ag<br>
                            <sub>12</sub><br>
                            Te<br>
                            <sub>6</sub><br>
                             framework and a linear Te atom chain running along the c axis. The super-space group of the framework was determined to be P6<br>
                            <sub>3</sub><br>
                            (00γ)s with a = b = 11.438(1) Å, c = 4.6256(5) Å, and that of the Te chain substructure has the same a and b axes, but c = 3.212(1) Å, space group P6(00γ)s. The modulation leads to the formation of Te<br>
                            <sub>2</sub><br>
                             and Te<br>
                            <sub>3</sub><br>
                             fragments in this chain and a refined formula of Tl<br>
                            <sub>2</sub><br>
                            Ag<br>
                            <sub>11.5</sub><br>
                            Te<br>
                            <sub>7.4</sub><br>
                            . The structure consists of a complex network of three-dimensionally connected AgTe<br>
                            <sub>4</sub><br>
                             tetrahedra forming channels filled with the Tl atoms. The electronic structures of four different models comprising different Te chains, Tl<br>
                            <sub>2</sub><br>
                            Ag<br>
                            <sub>12</sub><br>
                            Te<br>
                            <sub>7</sub><br>
                            , Tl<br>
                            <sub>2</sub><br>
                            Ag<br>
                            <sub>12</sub><br>
                            Te<br>
                            <sub>7.33</sub><br>
                            , and 2× Tl<br>
                            <sub>2</sub><br>
                            Ag<br>
                            <sub>12</sub><br>
                            Te<br>
                            <sub>7.5</sub><br>
                            , were computed using the WIEN2k package. Depending on the Te content within the chain, the models are either semiconducting or metallic. Physical property measurements revealed semiconducting properties, with an ultralow thermal conductivity, and excellent thermoelectric properties at elevated temperatures.<br>
                        </p>},
  author       = {Shi, Yixuan and Assoud, Abdeljalil and Ponou, Simeon and Lidin, Sven and Kleinke, Holger},
  issn         = {0002-7863},
  language     = {eng},
  month        = {07},
  number       = {27},
  pages        = {8578--8585},
  publisher    = {The American Chemical Society (ACS)},
  series       = {Journal of the American Chemical Society},
  title        = {A New Material with a Composite Crystal Structure Causing Ultralow Thermal Conductivity and Outstanding Thermoelectric Properties : Tl
                        <sub>2</sub>
                        Ag
                        <sub>12</sub>
                        Te
                        <sub>7+δ</sub>},
  url          = {http://dx.doi.org/10.1021/jacs.8b04639},
  doi          = {10.1021/jacs.8b04639},
  volume       = {140},
  year         = {2018},
}