Synthesis and Crystal Structure of a New Quaternary Thioantimonate, Na₉Gd₅Sb₈S₂₆

ISSN： 0022-4596

Source： Journal of Solid State Chemistry, Vol.161, Iss.1, 2001-10, pp. : 129-134

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Abstract

The first Na-containing quaternary rare-earth thioantimonate, Na₉Gd₅Sb₈S₂₆, was synthesized from the reaction of Gd metal, Sb, and S in Na₂S flux at 750°C. Black plate-shaped crystals were obtained and their crystal structure was determined by the single-crystal X-ray diffraction method. This compound crystallizes in the orthorhombic space group Pnma (No. 62) with a unit cell of a=11.406(3) Å, b=23.765(2) Å, c=16.923(5) Å, and Z=4. Na₉Gd₅Sb₈S₂₆ has a complex three-dimensional structure that consists of SbS₃, SbS₄, GdS₆, and GdS₇ units. In the structure, three crystallographically different Gd atoms form a staircase-shaped building block, where two Gd atoms share disulfide ions, S^2-₂. The formula of the compound can be described as (Na⁺)₉(Gd³⁺)₅(Sb³⁺)₈(S^2-)₂₂(S^2-₂)₂. Measurement of the optically diffuse reflectance indicates that Na₉Gd₅Sb₈S₂₆ is a semiconductor with a band gap of 1.63 eV.