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Metastable Cd4Sb3 : A complex structured intermetallic compound with semiconductor properties

Tengå, Andreas ; Lidin, Sven LU ; Belieres, Jean Philippe ; Newman, N. ; Wu, Yang and Häussermann, Ulrich (2008) In Journal of the American Chemical Society 130(46). p.15564-15572
Abstract

The metastable binary intermetallic compound Cd4Sb3 was obtained as polycrystalline ingot by quenching stoichiometric Cd-Sb melts and as mm-sized crystals by employing Bi or Sn fluxes. The compound crystallizes in the monoclinic space group Pn with a = 11.4975(5) Å, b = 26.126(1) Å, c = 26.122(1) Å, β = 100.77(1)°, and V = 7708.2(5) A,̊3. The actual formula unit of Cd4Sb3 is Cd13Sb10 and the unit cell contains 156 Cd and 120 Sb atoms (Z = 12). Cd4Sb3 displays a reversible order-disorder transition at 373 K and decomposes exothermically into a mixture of elemental Cd and CdSb at around 520 K. Disordered β-Cd 4Sb3 is... (More)

The metastable binary intermetallic compound Cd4Sb3 was obtained as polycrystalline ingot by quenching stoichiometric Cd-Sb melts and as mm-sized crystals by employing Bi or Sn fluxes. The compound crystallizes in the monoclinic space group Pn with a = 11.4975(5) Å, b = 26.126(1) Å, c = 26.122(1) Å, β = 100.77(1)°, and V = 7708.2(5) A,̊3. The actual formula unit of Cd4Sb3 is Cd13Sb10 and the unit cell contains 156 Cd and 120 Sb atoms (Z = 12). Cd4Sb3 displays a reversible order-disorder transition at 373 K and decomposes exothermically into a mixture of elemental Cd and CdSb at around 520 K. Disordered β-Cd 4Sb3 is rhombohedral (space group R3c, a ≈ 13.04 Å, c ≈ 13.03 Å) with a framework isostructural to β-Zn 4Sb3. The structure of monoclinic α-Cd 4Sb3 bears resemblance to the low-temperature modifications of Zn4Sb3, α- and α′- Zn4Sb3, in that randomly distributed vacancies and interstitial atoms of the high-temperature modification aggregate and order into distinct arrays. However, the nature of aggregation and distribution of aggregates is different in the two systems. Cd4Sb3 displays the properties of a narrow gap semiconductor. Between 10 and 350 K the resistivity of melt-quenched samples first increases with increasing temperature until a maximum value at 250 K and then decreases again. The resistivity maximum is accompanied with a discontinuity in the thermopower, which is positive and increasing from 10 to 350 K. The room temperature values of the resistivity and thermopower are about 25 mΩcm and 160 μV/K, respectively. Flux synthesized samples show altered properties due to the incorporation of small amounts of Bi or Sn (less than 1 at. %). Thermopower and resistivity appear drastically increased for Sn doped samples. Characteristic for Cd4Sb3 samples is their low thermal conductivity, which drops below 1 W/mK above 130 K and attains values around 0.75 W/mK at room temperature, which is comparable to vitreous materials.

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publication status
published
in
Journal of the American Chemical Society
volume
130
issue
46
pages
9 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • scopus:56449118604
ISSN
0002-7863
DOI
10.1021/ja805454p
language
English
LU publication?
no
id
86e9dbec-9d4a-4b7e-9355-6f976caed8ea
date added to LUP
2019-04-08 15:09:18
date last changed
2022-04-25 22:40:38
@article{86e9dbec-9d4a-4b7e-9355-6f976caed8ea,
  abstract     = {{<p>The metastable binary intermetallic compound Cd<sub>4</sub>Sb<sub>3</sub> was obtained as polycrystalline ingot by quenching stoichiometric Cd-Sb melts and as mm-sized crystals by employing Bi or Sn fluxes. The compound crystallizes in the monoclinic space group Pn with a = 11.4975(5) Å, b = 26.126(1) Å, c = 26.122(1) Å, β = 100.77(1)°, and V = 7708.2(5) A,̊<sup>3</sup>. The actual formula unit of Cd<sub>4</sub>Sb<sub>3</sub> is Cd<sub>13</sub>Sb<sub>10</sub> and the unit cell contains 156 Cd and 120 Sb atoms (Z = 12). Cd<sub>4</sub>Sb<sub>3</sub> displays a reversible order-disorder transition at 373 K and decomposes exothermically into a mixture of elemental Cd and CdSb at around 520 K. Disordered β-Cd <sub>4</sub>Sb<sub>3</sub> is rhombohedral (space group R3c, a ≈ 13.04 Å, c ≈ 13.03 Å) with a framework isostructural to β-Zn <sub>4</sub>Sb<sub>3</sub>. The structure of monoclinic α-Cd <sub>4</sub>Sb<sub>3</sub> bears resemblance to the low-temperature modifications of Zn<sub>4</sub>Sb<sub>3</sub>, α- and α′- Zn4Sb3, in that randomly distributed vacancies and interstitial atoms of the high-temperature modification aggregate and order into distinct arrays. However, the nature of aggregation and distribution of aggregates is different in the two systems. Cd<sub>4</sub>Sb<sub>3</sub> displays the properties of a narrow gap semiconductor. Between 10 and 350 K the resistivity of melt-quenched samples first increases with increasing temperature until a maximum value at 250 K and then decreases again. The resistivity maximum is accompanied with a discontinuity in the thermopower, which is positive and increasing from 10 to 350 K. The room temperature values of the resistivity and thermopower are about 25 mΩcm and 160 μV/K, respectively. Flux synthesized samples show altered properties due to the incorporation of small amounts of Bi or Sn (less than 1 at. %). Thermopower and resistivity appear drastically increased for Sn doped samples. Characteristic for Cd<sub>4</sub>Sb<sub>3</sub> samples is their low thermal conductivity, which drops below 1 W/mK above 130 K and attains values around 0.75 W/mK at room temperature, which is comparable to vitreous materials.</p>}},
  author       = {{Tengå, Andreas and Lidin, Sven and Belieres, Jean Philippe and Newman, N. and Wu, Yang and Häussermann, Ulrich}},
  issn         = {{0002-7863}},
  language     = {{eng}},
  month        = {{11}},
  number       = {{46}},
  pages        = {{15564--15572}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{Journal of the American Chemical Society}},
  title        = {{Metastable Cd<sub>4</sub>Sb<sub>3</sub> : A complex structured intermetallic compound with semiconductor properties}},
  url          = {{http://dx.doi.org/10.1021/ja805454p}},
  doi          = {{10.1021/ja805454p}},
  volume       = {{130}},
  year         = {{2008}},
}