Effects of alloying on band gap and morphology of iron pyrite nanoparticles

•Zinc alloyed FeS2 nanoparticles are synthesized first time only in oleylamine.•Alloying of zinc is confirmed with the blue-shift observed in Raman spectra.•An increase of 0.08 eV is observed in energy band-gap due to zinc alloying.•Nanoparticles shape changes from cubic to quasi cubic.

Here, we report the effects of zinc alloying in iron pyrite (FeS2) nanoparticles (NPs). The NPs were synthesized by a hot-injection method using oleylamine (OAm) only, with no other ligand. The band-gap and morphology were found to be strongly dependent on the relative amount of zinc incorporated in the nanoparticles. A blue shift was observed in Raman active modes for FeS2 upon Zn incorporation which has been ascribed to the change in the bond length of (S2)2− dumbbells in the pyrite structure. According to the optical absorption measurements the band-gap (Eg) of NPs increased linearly with the mole fraction of Zn in the precursor solution (Zni) for the NP synthesis, and an enhancement of ∼0.08 eV was achieved for Zni = 40%. Also, the shape of NPs varied from cubic to quasi-cubic with the increase in the mole fraction of Zn in the precursor.