Synthesis of Bi2−2xSb2xS3 (0 ≤ x ≤ 1) solid solutions from solventless thermolysis of metal xanthate precursors

Abstract

Tris(O-ethylxanthate)bismuth(III) (1) and tris(O-ethylxanthate)antimony(III) (2) were synthesized and used as precursors for the preparation of Bi_2−2xSb_2xS₃ alloys (x = 0, 0.2, 0.4, 0.6, 0.8 and 1) using solventless thermolysis. The p-XRD peaks at all ratios corresponded well to an orthorhombic crystal structure between that of Bi₂S₃ and Sb₂S₃. The lattice parameters a and b were found to increase linearly as the Sb content increases in the Bi_2−2xSb_2xS₃ samples, whereas c decreases gradually with increasing Sb. For all samples the elemental composition and uniform stoichiometry was determined by EDX analysis and ICP-OES. Incorporation of Sb into Bi₂S₃ led to an increase in the band gap from 1.66 eV at x = 0 to 2.19 eV at x = 1. The morphologies of the alloys were investigated using SEM, revealing different texturing as the composition changes from Bi₂S₃ to Sb₂S₃.