Molten salt synthesis and properties of three new solid-state ternary bismuth chalcogenides, β-CsBiS2, γ-CsBiS2, and K2Bi8Se13

Timothy J. McCarthy, Stanley Pierre Ngeyi, Ju Hsiou Liao, Donald C. DeGroot, Tim Hogan, Carl R. Kannewurf, Mercouri G Kanatzidis

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Abstract

β-CsBiS2, γ-CsBiS2, and K2Bi8Se13 were synthesized by the alkali metal polychalcogenide flux technique. An investigation of the Bi/CsSx system at 290°C revealed the presence of a new ternary sulfide β-CsBiS2 (I) (83 % yield). The red substance crystallizes in the monoclinic P21/c space group (No. 14) with a = 7.794(5) Å, b = 9.610(6) Å, c = 7.329(4) Å, β = 102.16(5)°. The final R/Rw = 7.4/10%. The structure consists of BiS3 trigonal pyramids connected at two vertices to form (BiS2)nn- chains along the a axis with Cs+ ions in between the chains. β-CsBiS2 is an insulator. γ-CsBiS2 was obtained as above but at 350°C. It crystallizes in the rhombohedral system with a = 4.166(4) Å and c = 48.77(5) Å. It has a superstructure related to that of RbBiS2. Similar investigations in the Bi/K2Sex system at 330°C gave the new ternary selenide K2Bi8Se13 (II) (88% yield). This compound crystallizes in the triclinic P1 space group (No. 2) with a = 13.768(2) Å, b = 12.093(3) Å, c = 4.1656(6) Å, α = 89.98(1)°, β = 98.64(1)°, γ= 87.96(1)°. The final R/Rw = 8.2/8.9%. The structure of the black crystals consists of layers of BiSe6 octahedra with BiSe5 square pyramidal units connecting the layers to form a three-dimensional network with K+ ions located in the channels. The [Bi8Se13]2- framework can be thought of as a hybrid of three different layered structure types interconnected to form a 3-D network. Structural features from the Bi2Te3, Sb2S3, and CdI2 lattices are represented in this framework. Electrical conductivity and thermopower measurements on γ-CsBiS2 and K2Bi8Se13 show n-type semiconducting behavior. For both materials the room temperature conductivity is ∼10-2 S/cm. The reaction of Bi with Cs2Sx and K2Sex fluxes was investigated with differential scanning calorimetry (DSC). The optical band gaps of β-CsBiS2, γ-CsBiS2, and K2Bi8Se13 were determined by UV/vis/near-IR diffuse reflectance measurements to be 1.43,1.11, and 0.76 eV, respectively.

Original languageEnglish
Pages (from-to)331-340
Number of pages10
JournalChemistry of Materials
Volume5
Issue number3
Publication statusPublished - 1993

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Chalcogenides
Bismuth
Molten materials
Salts
Ions
Fluxes
Alkali Metals
Reflectometers
Thermoelectric power
Optical band gaps
Alkali metals
Sulfides
Differential scanning calorimetry
Crystals
Temperature
Electric Conductivity

ASJC Scopus subject areas

  • Materials Chemistry
  • Materials Science(all)

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McCarthy, T. J., Ngeyi, S. P., Liao, J. H., DeGroot, D. C., Hogan, T., Kannewurf, C. R., & Kanatzidis, M. G. (1993). Molten salt synthesis and properties of three new solid-state ternary bismuth chalcogenides, β-CsBiS2, γ-CsBiS2, and K2Bi8Se13. Chemistry of Materials, 5(3), 331-340.

Molten salt synthesis and properties of three new solid-state ternary bismuth chalcogenides, β-CsBiS2, γ-CsBiS2, and K2Bi8Se13. / McCarthy, Timothy J.; Ngeyi, Stanley Pierre; Liao, Ju Hsiou; DeGroot, Donald C.; Hogan, Tim; Kannewurf, Carl R.; Kanatzidis, Mercouri G.

In: Chemistry of Materials, Vol. 5, No. 3, 1993, p. 331-340.

Research output: Contribution to journalArticle

McCarthy, Timothy J. ; Ngeyi, Stanley Pierre ; Liao, Ju Hsiou ; DeGroot, Donald C. ; Hogan, Tim ; Kannewurf, Carl R. ; Kanatzidis, Mercouri G. / Molten salt synthesis and properties of three new solid-state ternary bismuth chalcogenides, β-CsBiS2, γ-CsBiS2, and K2Bi8Se13. In: Chemistry of Materials. 1993 ; Vol. 5, No. 3. pp. 331-340.
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title = "Molten salt synthesis and properties of three new solid-state ternary bismuth chalcogenides, β-CsBiS2, γ-CsBiS2, and K2Bi8Se13",
abstract = "β-CsBiS2, γ-CsBiS2, and K2Bi8Se13 were synthesized by the alkali metal polychalcogenide flux technique. An investigation of the Bi/CsSx system at 290°C revealed the presence of a new ternary sulfide β-CsBiS2 (I) (83 {\%} yield). The red substance crystallizes in the monoclinic P21/c space group (No. 14) with a = 7.794(5) {\AA}, b = 9.610(6) {\AA}, c = 7.329(4) {\AA}, β = 102.16(5)°. The final R/Rw = 7.4/10{\%}. The structure consists of BiS3 trigonal pyramids connected at two vertices to form (BiS2)nn- chains along the a axis with Cs+ ions in between the chains. β-CsBiS2 is an insulator. γ-CsBiS2 was obtained as above but at 350°C. It crystallizes in the rhombohedral system with a = 4.166(4) {\AA} and c = 48.77(5) {\AA}. It has a superstructure related to that of RbBiS2. Similar investigations in the Bi/K2Sex system at 330°C gave the new ternary selenide K2Bi8Se13 (II) (88{\%} yield). This compound crystallizes in the triclinic P1 space group (No. 2) with a = 13.768(2) {\AA}, b = 12.093(3) {\AA}, c = 4.1656(6) {\AA}, α = 89.98(1)°, β = 98.64(1)°, γ= 87.96(1)°. The final R/Rw = 8.2/8.9{\%}. The structure of the black crystals consists of layers of BiSe6 octahedra with BiSe5 square pyramidal units connecting the layers to form a three-dimensional network with K+ ions located in the channels. The [Bi8Se13]2- framework can be thought of as a hybrid of three different layered structure types interconnected to form a 3-D network. Structural features from the Bi2Te3, Sb2S3, and CdI2 lattices are represented in this framework. Electrical conductivity and thermopower measurements on γ-CsBiS2 and K2Bi8Se13 show n-type semiconducting behavior. For both materials the room temperature conductivity is ∼10-2 S/cm. The reaction of Bi with Cs2Sx and K2Sex fluxes was investigated with differential scanning calorimetry (DSC). The optical band gaps of β-CsBiS2, γ-CsBiS2, and K2Bi8Se13 were determined by UV/vis/near-IR diffuse reflectance measurements to be 1.43,1.11, and 0.76 eV, respectively.",
author = "McCarthy, {Timothy J.} and Ngeyi, {Stanley Pierre} and Liao, {Ju Hsiou} and DeGroot, {Donald C.} and Tim Hogan and Kannewurf, {Carl R.} and Kanatzidis, {Mercouri G}",
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T1 - Molten salt synthesis and properties of three new solid-state ternary bismuth chalcogenides, β-CsBiS2, γ-CsBiS2, and K2Bi8Se13

AU - McCarthy, Timothy J.

AU - Ngeyi, Stanley Pierre

AU - Liao, Ju Hsiou

AU - DeGroot, Donald C.

AU - Hogan, Tim

AU - Kannewurf, Carl R.

AU - Kanatzidis, Mercouri G

PY - 1993

Y1 - 1993

N2 - β-CsBiS2, γ-CsBiS2, and K2Bi8Se13 were synthesized by the alkali metal polychalcogenide flux technique. An investigation of the Bi/CsSx system at 290°C revealed the presence of a new ternary sulfide β-CsBiS2 (I) (83 % yield). The red substance crystallizes in the monoclinic P21/c space group (No. 14) with a = 7.794(5) Å, b = 9.610(6) Å, c = 7.329(4) Å, β = 102.16(5)°. The final R/Rw = 7.4/10%. The structure consists of BiS3 trigonal pyramids connected at two vertices to form (BiS2)nn- chains along the a axis with Cs+ ions in between the chains. β-CsBiS2 is an insulator. γ-CsBiS2 was obtained as above but at 350°C. It crystallizes in the rhombohedral system with a = 4.166(4) Å and c = 48.77(5) Å. It has a superstructure related to that of RbBiS2. Similar investigations in the Bi/K2Sex system at 330°C gave the new ternary selenide K2Bi8Se13 (II) (88% yield). This compound crystallizes in the triclinic P1 space group (No. 2) with a = 13.768(2) Å, b = 12.093(3) Å, c = 4.1656(6) Å, α = 89.98(1)°, β = 98.64(1)°, γ= 87.96(1)°. The final R/Rw = 8.2/8.9%. The structure of the black crystals consists of layers of BiSe6 octahedra with BiSe5 square pyramidal units connecting the layers to form a three-dimensional network with K+ ions located in the channels. The [Bi8Se13]2- framework can be thought of as a hybrid of three different layered structure types interconnected to form a 3-D network. Structural features from the Bi2Te3, Sb2S3, and CdI2 lattices are represented in this framework. Electrical conductivity and thermopower measurements on γ-CsBiS2 and K2Bi8Se13 show n-type semiconducting behavior. For both materials the room temperature conductivity is ∼10-2 S/cm. The reaction of Bi with Cs2Sx and K2Sex fluxes was investigated with differential scanning calorimetry (DSC). The optical band gaps of β-CsBiS2, γ-CsBiS2, and K2Bi8Se13 were determined by UV/vis/near-IR diffuse reflectance measurements to be 1.43,1.11, and 0.76 eV, respectively.

AB - β-CsBiS2, γ-CsBiS2, and K2Bi8Se13 were synthesized by the alkali metal polychalcogenide flux technique. An investigation of the Bi/CsSx system at 290°C revealed the presence of a new ternary sulfide β-CsBiS2 (I) (83 % yield). The red substance crystallizes in the monoclinic P21/c space group (No. 14) with a = 7.794(5) Å, b = 9.610(6) Å, c = 7.329(4) Å, β = 102.16(5)°. The final R/Rw = 7.4/10%. The structure consists of BiS3 trigonal pyramids connected at two vertices to form (BiS2)nn- chains along the a axis with Cs+ ions in between the chains. β-CsBiS2 is an insulator. γ-CsBiS2 was obtained as above but at 350°C. It crystallizes in the rhombohedral system with a = 4.166(4) Å and c = 48.77(5) Å. It has a superstructure related to that of RbBiS2. Similar investigations in the Bi/K2Sex system at 330°C gave the new ternary selenide K2Bi8Se13 (II) (88% yield). This compound crystallizes in the triclinic P1 space group (No. 2) with a = 13.768(2) Å, b = 12.093(3) Å, c = 4.1656(6) Å, α = 89.98(1)°, β = 98.64(1)°, γ= 87.96(1)°. The final R/Rw = 8.2/8.9%. The structure of the black crystals consists of layers of BiSe6 octahedra with BiSe5 square pyramidal units connecting the layers to form a three-dimensional network with K+ ions located in the channels. The [Bi8Se13]2- framework can be thought of as a hybrid of three different layered structure types interconnected to form a 3-D network. Structural features from the Bi2Te3, Sb2S3, and CdI2 lattices are represented in this framework. Electrical conductivity and thermopower measurements on γ-CsBiS2 and K2Bi8Se13 show n-type semiconducting behavior. For both materials the room temperature conductivity is ∼10-2 S/cm. The reaction of Bi with Cs2Sx and K2Sex fluxes was investigated with differential scanning calorimetry (DSC). The optical band gaps of β-CsBiS2, γ-CsBiS2, and K2Bi8Se13 were determined by UV/vis/near-IR diffuse reflectance measurements to be 1.43,1.11, and 0.76 eV, respectively.

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