The quaternary Cs2S/Bi/As/S system was studied in an attempt to introduce two different asymmetric but isoelectronic building units, namely, [BiIIIxSy] and [AsIII xSy], in a single structure. Reactions with a comparatively lower equivalent of arsenic in the Cs2S/Bi/As/S mixture led to the crystalline compound Cs3Bi(AsS4)2. The structure features tetrahedral [AsVS4]3- connected to BiIII centers to give infinite 1/ ∞[Bi(AsS4)23-] chains. When the basicity was raised in these low arsenic fluxes by increasing the Cs 2S fraction, the crystalline compound Cs9Bi(AsS 4)4, also featuring [AsVS4] 3- anions, was formed. On the other hand, arsenic-rich mixtures of Cs2S/Bi/As/S led to the formation of the glassy phase Cs 2BiAs3S7, which contains AsIII species. X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and pair distribution function (PDF) analysis indicate the presence of As III-containing [AsnS2n+1] fragments in the glass structure. Several glasses in the series Csn-1BiAs nS2n+1 were also prepared using solid-state fusion reactions. The band gaps of the Csn-1BiAsnS2n+1 glasses are in the range of 1.51-1.81 eV, while that of the crystalline compound Cs3Bi(AsS4)2 is ∼2.33 eV. The thermal and optical behaviors of these compounds are correlated with their structures and building units.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry