High Thermopower and Low Thermal Conductivity in Semiconducting Ternary K-Bi-Se Compounds. Synthesis and Properties of β-K2Bi8Se13 and K2.5Bi8.5Se14 and Their Sb Analogues

Duck Young Chung, Kyoung Shin Choi, Lykourgos Iordanidis, Jon L. Schindler, Paul W. Brazis, Carl R. Kannewurf, Baoxing Chen, Siqing Hu, Ctirad Uher, Mercouri G Kanatzidis

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Abstract

β-K2Bi8Se13 (I), K2Sb8Se13 (II), K2.5Bi8.5Se14 (III), and K2.5Sb8.5Se14 (IV) were synthesized by a molten flux method. The black needles of compound I were formed at 600 °C and crystallized in the monoclinic P21/m space group (No. 11) with a -17.492(3) Å, b = 4.205(1) Å, c= 18.461(4) Å, β= 90.49(2)°. The final R/Rw = 6.7/5.7%. Compound II is isostructural to I. Both I and II are isostructural with K2Bi8S13 which is composed of NaCl-, Bi2Te3-, and CdI2-type units connecting to form K+-filled channels. The thin black needles of III and IV obtained at 530 °C crystallize in the same space group P21/m with a -17.534(4) Å, b = 4.206(1) Å, c = 21.387(5) Å, β= 109.65(2)° and a = 17.265(3) Å, b = 4.0801(9) Å, c = 21.280(3) Å, β = 109.31(1)°, respectively. The final R/Rw = 6.3/8.3% and 5.1/3.6%-. Compounds III and IV are isostructural and potassium and bismuth/antimony atoms are disordered over two crystallographic sites. The structure type is very closely related to that of I. Electrical conductivity and thermopower measurements show semiconductor behavior with ∼250 S/cm and ∼-200 μV/K for a single crystal of I and ∼150 S/cm and ∼-100 μV/K for a polycrystalline ingot of III at room temperature. The effect of vaccum annealing on these compounds is explored. The optical bandgaps of all compounds were determined to be 0.59, 0.78, 0.56, and 0.82 eV, respectively. The thermal conductivities of melt-grown polycrystalline ingots of I and III are reported.

Original languageEnglish
Pages (from-to)3060-3071
Number of pages12
JournalChemistry of Materials
Volume9
Issue number12
Publication statusPublished - Dec 1997

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Thermoelectric power
Ingots
Needles
Thermal conductivity
Antimony
Bismuth
Optical band gaps
Potassium
Molten materials
Single crystals
Annealing
Semiconductor materials
Fluxes
Atoms
Temperature
Electric Conductivity

ASJC Scopus subject areas

  • Materials Science(all)
  • Materials Chemistry

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High Thermopower and Low Thermal Conductivity in Semiconducting Ternary K-Bi-Se Compounds. Synthesis and Properties of β-K2Bi8Se13 and K2.5Bi8.5Se14 and Their Sb Analogues. / Chung, Duck Young; Choi, Kyoung Shin; Iordanidis, Lykourgos; Schindler, Jon L.; Brazis, Paul W.; Kannewurf, Carl R.; Chen, Baoxing; Hu, Siqing; Uher, Ctirad; Kanatzidis, Mercouri G.

In: Chemistry of Materials, Vol. 9, No. 12, 12.1997, p. 3060-3071.

Research output: Contribution to journalArticle

Chung, DY, Choi, KS, Iordanidis, L, Schindler, JL, Brazis, PW, Kannewurf, CR, Chen, B, Hu, S, Uher, C & Kanatzidis, MG 1997, 'High Thermopower and Low Thermal Conductivity in Semiconducting Ternary K-Bi-Se Compounds. Synthesis and Properties of β-K2Bi8Se13 and K2.5Bi8.5Se14 and Their Sb Analogues', Chemistry of Materials, vol. 9, no. 12, pp. 3060-3071.
Chung, Duck Young ; Choi, Kyoung Shin ; Iordanidis, Lykourgos ; Schindler, Jon L. ; Brazis, Paul W. ; Kannewurf, Carl R. ; Chen, Baoxing ; Hu, Siqing ; Uher, Ctirad ; Kanatzidis, Mercouri G. / High Thermopower and Low Thermal Conductivity in Semiconducting Ternary K-Bi-Se Compounds. Synthesis and Properties of β-K2Bi8Se13 and K2.5Bi8.5Se14 and Their Sb Analogues. In: Chemistry of Materials. 1997 ; Vol. 9, No. 12. pp. 3060-3071.
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title = "High Thermopower and Low Thermal Conductivity in Semiconducting Ternary K-Bi-Se Compounds. Synthesis and Properties of β-K2Bi8Se13 and K2.5Bi8.5Se14 and Their Sb Analogues",
abstract = "β-K2Bi8Se13 (I), K2Sb8Se13 (II), K2.5Bi8.5Se14 (III), and K2.5Sb8.5Se14 (IV) were synthesized by a molten flux method. The black needles of compound I were formed at 600 °C and crystallized in the monoclinic P21/m space group (No. 11) with a -17.492(3) {\AA}, b = 4.205(1) {\AA}, c= 18.461(4) {\AA}, β= 90.49(2)°. The final R/Rw = 6.7/5.7{\%}. Compound II is isostructural to I. Both I and II are isostructural with K2Bi8S13 which is composed of NaCl-, Bi2Te3-, and CdI2-type units connecting to form K+-filled channels. The thin black needles of III and IV obtained at 530 °C crystallize in the same space group P21/m with a -17.534(4) {\AA}, b = 4.206(1) {\AA}, c = 21.387(5) {\AA}, β= 109.65(2)° and a = 17.265(3) {\AA}, b = 4.0801(9) {\AA}, c = 21.280(3) {\AA}, β = 109.31(1)°, respectively. The final R/Rw = 6.3/8.3{\%} and 5.1/3.6{\%}-. Compounds III and IV are isostructural and potassium and bismuth/antimony atoms are disordered over two crystallographic sites. The structure type is very closely related to that of I. Electrical conductivity and thermopower measurements show semiconductor behavior with ∼250 S/cm and ∼-200 μV/K for a single crystal of I and ∼150 S/cm and ∼-100 μV/K for a polycrystalline ingot of III at room temperature. The effect of vaccum annealing on these compounds is explored. The optical bandgaps of all compounds were determined to be 0.59, 0.78, 0.56, and 0.82 eV, respectively. The thermal conductivities of melt-grown polycrystalline ingots of I and III are reported.",
author = "Chung, {Duck Young} and Choi, {Kyoung Shin} and Lykourgos Iordanidis and Schindler, {Jon L.} and Brazis, {Paul W.} and Kannewurf, {Carl R.} and Baoxing Chen and Siqing Hu and Ctirad Uher and Kanatzidis, {Mercouri G}",
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T1 - High Thermopower and Low Thermal Conductivity in Semiconducting Ternary K-Bi-Se Compounds. Synthesis and Properties of β-K2Bi8Se13 and K2.5Bi8.5Se14 and Their Sb Analogues

AU - Chung, Duck Young

AU - Choi, Kyoung Shin

AU - Iordanidis, Lykourgos

AU - Schindler, Jon L.

AU - Brazis, Paul W.

AU - Kannewurf, Carl R.

AU - Chen, Baoxing

AU - Hu, Siqing

AU - Uher, Ctirad

AU - Kanatzidis, Mercouri G

PY - 1997/12

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N2 - β-K2Bi8Se13 (I), K2Sb8Se13 (II), K2.5Bi8.5Se14 (III), and K2.5Sb8.5Se14 (IV) were synthesized by a molten flux method. The black needles of compound I were formed at 600 °C and crystallized in the monoclinic P21/m space group (No. 11) with a -17.492(3) Å, b = 4.205(1) Å, c= 18.461(4) Å, β= 90.49(2)°. The final R/Rw = 6.7/5.7%. Compound II is isostructural to I. Both I and II are isostructural with K2Bi8S13 which is composed of NaCl-, Bi2Te3-, and CdI2-type units connecting to form K+-filled channels. The thin black needles of III and IV obtained at 530 °C crystallize in the same space group P21/m with a -17.534(4) Å, b = 4.206(1) Å, c = 21.387(5) Å, β= 109.65(2)° and a = 17.265(3) Å, b = 4.0801(9) Å, c = 21.280(3) Å, β = 109.31(1)°, respectively. The final R/Rw = 6.3/8.3% and 5.1/3.6%-. Compounds III and IV are isostructural and potassium and bismuth/antimony atoms are disordered over two crystallographic sites. The structure type is very closely related to that of I. Electrical conductivity and thermopower measurements show semiconductor behavior with ∼250 S/cm and ∼-200 μV/K for a single crystal of I and ∼150 S/cm and ∼-100 μV/K for a polycrystalline ingot of III at room temperature. The effect of vaccum annealing on these compounds is explored. The optical bandgaps of all compounds were determined to be 0.59, 0.78, 0.56, and 0.82 eV, respectively. The thermal conductivities of melt-grown polycrystalline ingots of I and III are reported.

AB - β-K2Bi8Se13 (I), K2Sb8Se13 (II), K2.5Bi8.5Se14 (III), and K2.5Sb8.5Se14 (IV) were synthesized by a molten flux method. The black needles of compound I were formed at 600 °C and crystallized in the monoclinic P21/m space group (No. 11) with a -17.492(3) Å, b = 4.205(1) Å, c= 18.461(4) Å, β= 90.49(2)°. The final R/Rw = 6.7/5.7%. Compound II is isostructural to I. Both I and II are isostructural with K2Bi8S13 which is composed of NaCl-, Bi2Te3-, and CdI2-type units connecting to form K+-filled channels. The thin black needles of III and IV obtained at 530 °C crystallize in the same space group P21/m with a -17.534(4) Å, b = 4.206(1) Å, c = 21.387(5) Å, β= 109.65(2)° and a = 17.265(3) Å, b = 4.0801(9) Å, c = 21.280(3) Å, β = 109.31(1)°, respectively. The final R/Rw = 6.3/8.3% and 5.1/3.6%-. Compounds III and IV are isostructural and potassium and bismuth/antimony atoms are disordered over two crystallographic sites. The structure type is very closely related to that of I. Electrical conductivity and thermopower measurements show semiconductor behavior with ∼250 S/cm and ∼-200 μV/K for a single crystal of I and ∼150 S/cm and ∼-100 μV/K for a polycrystalline ingot of III at room temperature. The effect of vaccum annealing on these compounds is explored. The optical bandgaps of all compounds were determined to be 0.59, 0.78, 0.56, and 0.82 eV, respectively. The thermal conductivities of melt-grown polycrystalline ingots of I and III are reported.

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