TY - JOUR
T1 - Effect of metal doping on the low-temperature structural behavior of thermoelectric β-Zn4Sb3
AU - Nylén, Johanna
AU - Lidin, Sven
AU - Andersson, Magnus
AU - Liu, Hongxue
AU - Newman, Nathan
AU - Häussermann, Ulrich
N1 - Funding Information:
We are grateful to Lukas Palatinus for introduction to and discussions of the method of charge flipping. This work was supported by the Swedish Research Council (VR). J.N. acknowledges support from the Bengt Lundqvist and K&A Wallenberg foundations.
PY - 2007/9
Y1 - 2007/9
N2 - The low-temperature structural phase transitions of Bi, Pb, In and Sn-doped samples of thermoelectric Zn4Sb3 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-Zn4Sb3 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-Zn4Sb3 is Zn13Sb10. 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-Zn4Sb3 structure. When preparing β-Zn4Sb3 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 Zn4Sb3 and has dramatic consequences for its low-temperature structural behavior. From molten metal flux synthesis it is possible to obtain (doped) Zn4Sb3 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′-Zn4Sb3. The crystallographic composition of this phase is Zn84Sb65.
AB - The low-temperature structural phase transitions of Bi, Pb, In and Sn-doped samples of thermoelectric Zn4Sb3 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-Zn4Sb3 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-Zn4Sb3 is Zn13Sb10. 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-Zn4Sb3 structure. When preparing β-Zn4Sb3 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 Zn4Sb3 and has dramatic consequences for its low-temperature structural behavior. From molten metal flux synthesis it is possible to obtain (doped) Zn4Sb3 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′-Zn4Sb3. The crystallographic composition of this phase is Zn84Sb65.
KW - Order-disorder structural transitions
KW - Temperature polymorphism
KW - Thermoelectric materials
KW - Zinc antimonides
UR - http://www.scopus.com/inward/record.url?scp=34548425737&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=34548425737&partnerID=8YFLogxK
U2 - 10.1016/j.jssc.2007.07.013
DO - 10.1016/j.jssc.2007.07.013
M3 - Article
AN - SCOPUS:34548425737
SN - 0022-4596
VL - 180
SP - 2603
EP - 2615
JO - Journal of Solid State Chemistry
JF - Journal of Solid State Chemistry
IS - 9
ER -