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Effect of metal doping on the low-temperature structural behavior of thermoelectric β-Zn 4 Sb 3

Nylén, Johanna ; Lidin, Sven LU ; Andersson, Magnus LU ; Liu, Hongxue ; Newman, Nate and Häussermann, Ulrich (2007) In Journal of Solid State Chemistry 180(9). p.2603-2615
Abstract


The low-temperature structural phase transitions of Bi, Pb, In and Sn-doped samples of thermoelectric Zn
4
Sb
3
have been characterized on crystals grown from molten metal fluxes, using electrical resistance and single crystal X-ray diffraction measurements. Room temperature stable, disordered, β-Zn
4
Sb
3
undergoes two phase transitions at 254 and 235 K to the consecutively higher ordered phases α and α′,... (More)


The low-temperature structural phase transitions of Bi, Pb, In and Sn-doped samples of thermoelectric Zn
4
Sb
3
have been characterized on crystals grown from molten metal fluxes, using electrical resistance and single crystal X-ray diffraction measurements. Room temperature stable, disordered, β-Zn
4
Sb
3
undergoes two phase transitions at 254 and 235 K to the consecutively higher ordered phases α and α′, respectively. The ideal crystallographic composition of α-Zn
4
Sb
3
is Zn
13
Sb
10
. The α-α′ transformation is triggered by a slight and homogenous Zn deficiency with respect to this composition and introduces a compositional modulation in the α-Zn
4
Sb
3
structure. When preparing β-Zn
4
Sb
3
in the presence of metals with low melting points (Bi, Sn, In, Pb) the additional metal atoms are unavoidably incorporated in small concentrations (0.04-1.3 at%) and act as dopants. This incorporation alters the subtle balance between Zn disorder and Zn deficiency in Zn
4
Sb
3
and has dramatic consequences for its low-temperature structural behavior. From molten metal flux synthesis it is possible to obtain (doped) Zn
4
Sb
3
samples which (1) only display a β-α transition, (2) only display a β-α′ transition, or (3) do not display any low-temperature phase transition at all. Case (2) provided diffraction data with a sufficient quality to obtain a structural model for highly complex, compositionally modulated, α′-Zn
4
Sb
3
. The crystallographic composition of this phase is Zn
84
Sb
65
.

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author
; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
keywords
Order-disorder structural transitions, Temperature polymorphism, Thermoelectric materials, Zinc antimonides
in
Journal of Solid State Chemistry
volume
180
issue
9
pages
13 pages
publisher
Elsevier
external identifiers
  • scopus:34548425737
ISSN
0022-4596
DOI
10.1016/j.jssc.2007.07.013
language
English
LU publication?
yes
id
31fa258e-6980-4835-a60c-59c2ead85483
date added to LUP
2019-04-08 15:14:01
date last changed
2020-12-08 01:36:16
@article{31fa258e-6980-4835-a60c-59c2ead85483,
  abstract     = {<p><br>
                            The low-temperature structural phase transitions of Bi, Pb, In and Sn-doped samples of thermoelectric Zn<br>
                            <sub>4</sub><br>
                            Sb<br>
                            <sub>3</sub><br>
                             have been characterized on crystals grown from molten metal fluxes, using electrical resistance and single crystal X-ray diffraction measurements. Room temperature stable, disordered, β-Zn<br>
                            <sub>4</sub><br>
                            Sb<br>
                            <sub>3</sub><br>
                             undergoes two phase transitions at 254 and 235 K to the consecutively higher ordered phases α and α′, respectively. The ideal crystallographic composition of α-Zn<br>
                            <sub>4</sub><br>
                            Sb<br>
                            <sub>3</sub><br>
                             is Zn<br>
                            <sub>13</sub><br>
                            Sb<br>
                            <sub>10</sub><br>
                            . The α-α′ transformation is triggered by a slight and homogenous Zn deficiency with respect to this composition and introduces a compositional modulation in the α-Zn<br>
                            <sub>4</sub><br>
                            Sb<br>
                            <sub>3</sub><br>
                             structure. When preparing β-Zn<br>
                            <sub>4</sub><br>
                            Sb<br>
                            <sub>3</sub><br>
                             in the presence of metals with low melting points (Bi, Sn, In, Pb) the additional metal atoms are unavoidably incorporated in small concentrations (0.04-1.3 at%) and act as dopants. This incorporation alters the subtle balance between Zn disorder and Zn deficiency in Zn<br>
                            <sub>4</sub><br>
                            Sb<br>
                            <sub>3</sub><br>
                             and has dramatic consequences for its low-temperature structural behavior. From molten metal flux synthesis it is possible to obtain (doped) Zn<br>
                            <sub>4</sub><br>
                            Sb<br>
                            <sub>3</sub><br>
                             samples which (1) only display a β-α transition, (2) only display a β-α′ transition, or (3) do not display any low-temperature phase transition at all. Case (2) provided diffraction data with a sufficient quality to obtain a structural model for highly complex, compositionally modulated, α′-Zn<br>
                            <sub>4</sub><br>
                            Sb<br>
                            <sub>3</sub><br>
                            . The crystallographic composition of this phase is Zn<br>
                            <sub>84</sub><br>
                            Sb<br>
                            <sub>65</sub><br>
                            .</p>},
  author       = {Nylén, Johanna and Lidin, Sven and Andersson, Magnus and Liu, Hongxue and Newman, Nate and Häussermann, Ulrich},
  issn         = {0022-4596},
  language     = {eng},
  month        = {09},
  number       = {9},
  pages        = {2603--2615},
  publisher    = {Elsevier},
  series       = {Journal of Solid State Chemistry},
  title        = {Effect of metal doping on the low-temperature structural behavior of thermoelectric β-Zn
                        <sub>4</sub>
                        Sb
                        <sub>3</sub>},
  url          = {http://dx.doi.org/10.1016/j.jssc.2007.07.013},
  doi          = {10.1016/j.jssc.2007.07.013},
  volume       = {180},
  year         = {2007},
}