Synthesis in molten alkali metal polythiophosphate fluxes. The new quaternary bismuth and antimony thiophosphates ABiP2S7 (A = K, Rb), A3M(PS4)2 (A = K, Rb, Cs; M = Sb, Bi), Cs3Bi2(PS4)3, and Na0.16Bi1.28P2S6

Timothy McCarthy, Mercouri G. Kanatzidis

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We used the molten alkali metal polychalcogenide flux method to prepare the new compounds ABiP2S7 (A = K, Rb), A3M(PS4)2 (A = K, Rb, Cs; M = Sb, Bi), Cs3Bi2(PS4)3, and Na0.16Bi1.28P2S6. KBiP2S7 crystallizes in the monoclinic space group P21/c with a = 9.500(3) Å, b = 12.303(4) Å, c = 9.097(3) Å, β = 90.59(3), V = 1063 Å3, at 23°C. Dcalc = 3.34 g cm-3, μ = 184.85 cm-1, 2θmax = 50 Mo Kα. Data with I>3σ-(I) 1672, R/Rw(%) = 2.8/3.1. K3Bi(PS4)2 crystallizes in the orthorhombic space group P212121 with a = 23.894(8)(3) Å, b = 6.799(3) Å, c = 9.049(2) Å, V = 1470 Å3, at -60°C. Dcalc = 2.91 g cm-3, μ = 140.8 cm-1, 2θmax = 50. Data with I>3σ(I) 1745, R/Rw(%) = 5.5/6.0. Cs3Bi2(PS4)3 crystallizes in the monoclinic space group P21/c with a = 18.091(5) Å, b = 6.791(2) Å, c = 18.723(3) Å, β = 97.95(2), V = 2278 Å3, at 23°C. Dcalc = 3.77 g cm-3, μ = 213.3 cm-1, 2θmax = 50. Data with I>3σ(I) 2623, R/Rw(%) = 7.0/9.0. Na0.16Bi1.28P2S6 crystallizes in the monoclinic space group F21/n with a = 6.554(2) Å, b = 7.297(2) Å, c = 9.371(1) Å, β = 92.04(2), V = 447.8 Å3, at 23°C. Dcalc = 3.73 g cm-3, μ = 236.2 cm-1, 2θmax = 50. Data with I>3σ(I) 892, R/Rw(%) = 7.7/8.5. The structural diversity in this family of compounds ranges from the one-dimensional non-centrosymmetric chains of A3M(PS4)2 and the layered compounds, ABiP2S7 and Cs3Bi2(PS4)2, to the dense three-dimensional framework of Na0.16Bi1.28P2S6. KBiP2S7 is a layered solid with a complex new structure type, where corrugated layers are separated by eight-coordinate K+ ions. It contains a [P2S7]4- ligand in a complicated coordination mode. The structure of K3Bi(PS4)2 is assembled from one-dimensional, helical [Bi(PS4)2]3n-n chains running along the crystallographic b-axis. The chain structure features two interesting binding modes for a tetrahedral [PS4]3- ligand. The structure of Cs3Bi2(PS4)3 has layers containing the same one-dimensional helical chains observed in K3Bi(PS4)2. However, the PS4 unit acts as a bridge to a Bi2(PS4)2 dimeric unit. This unit is linked to another chain via a second bridging PS4 ligand to form sheets that are parallel to the [101] crystallographic plane. The structure of Na0.16Bi1.28P2S6 is three dimensional but consists of layers of P2S6 groups in the a-b plane separated by a single layer of Bi3+ ions. The ethane-like [P2S6]4- ligand chelates to eight Bi atoms in a very convoluted fashion. Positional disorder was found between Na and Bi ions in one crystallographic site. Their synthesis, structural characterization, optical absorption and thermal properties are reported.

Original languageEnglish
Pages (from-to)70-85
Number of pages16
JournalJournal of Alloys and Compounds
Issue number1-2
Publication statusPublished - Apr 1 1996



  • Alkali polychalcogenide fluxes
  • Antimony
  • Bismuth
  • Properties
  • Quaternary thiophosphates
  • Synthesis

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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