Abstract
Simple Summary The phase diagram of the Fe-Sb-S system predicts that phase separation should occur at synthesis temperatures below 540 degrees C. In this paper we test the efficacy of alloying Fe into Sb2S3 using a molecular precursor approach which may be able to produce Fe-Sb-S alloys with a single pure phase. We find that whilst we do see a large degree of phase separation as predicted, we also find that there is some evidence that incorporation of Fe into the Sb2S3 host lattice occurs from this approach which could be a way to produce new magnetic materials. The antimony-iron sulfide system in general does not produce alloys below 540 degrees C from traditional solid-state methods. However, single source precursors have been known to produce unexpected products that arise from kinetically trapped polymorphs. In this paper, we test the efficacy of this approach toward the Fe-Sb-S system. Antimony and iron diethyldithiocarbamate complexes of the form Sb[S2CN(Et-2)](3) (1) and Fe[S2CN(Et-2)](3) (2) were synthesised, characterised, and used as single-source precursors for the preparation of Sb2S3, FexSy, and mixed iron antimony sulfide Sb2(1-x)Fe2xS3 (0 >= x >= 1) powders using the solvent-less thermolysis method at different temperatures ranging from 300 to 475 degrees C. The effect of different mole fractions of the iron precursor was evaluated on morphology, shape, and optical and magnetic properties of Sb2(1-x)Fe2xS3 (0 >= x >= 1). The obtained powders were characterized by X-ray diffraction (XRD), Raman spectroscopy scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, magnetometer measurement, and UV/vis/NIR spectroscopy. The results demonstrated that the crystalline structure, morphology, and elemental composition of the samples changed with the mole fraction of the precursor. There was significant phase separation between Sb and Fe sulfides noted from EDX spectroscopic mapping, yet an optoelectronic study monitoring the direct band gap energy of antimony sulfide shows that the band gap energy increases as a function of Fe content, which suggests limited alloying is possible from the single source route.