γ-MnS nano and micro architectures: Synthesis, characterization and optical properties

γ-MnS nanocrystalline materials have been prepared by reaction of Na2[Mn(HL)2(H2O)2]; 1:2 (M:L) chelate complex with alkaline solution of thiocarbamide in aqueous solution phase. Effect of metal chelate complex, reaction time and surfactant sodium dodecyl sulfate; SDS on phase, morphology and size of the products have been investigated. The metal chelate complex was synthesized by reacting Mn(II) ions with eriochrome black T (NaH2L) in alkaline medium. γ-MnS crystals were formed when metal complex was used as metal source whereas Mn3O4 was the dominant product when MnSO4·H2O was used as metal source. Materials thus formed having various morphologies were characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM) to determine the crystallinity, phase, structure and morphology. The optical properties of the thus prepared samples were determined by UV–vis absorption spectra and photoluminescence spectra. A possible formation mechanism of crystals has been discussed in this article.

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► In this article we have reported the formation of γ-MnS nano/microcrystalline material by a novel proposed route. Na2[Mn(HL)2(H2O)2]; 1:2 (M:L) chelate complex was synthesized in the first step by our previously reported method. The chelate complex precursor was subsequently decomposed by alkaline solution of thiocarbamide, resulting formation of γ-MnS crystals in situ.
► The effect of reaction time and surfactant have been observed and discussed. The materials were characterized for crystallanity and morphology by SEM, TEM, XRD, UV-Vis, PL spectra and the results are thoroughly discussed.
► γ-MnS crystals were formed when metal complex was used as metal source whereas Mn3O4 was the dominant product when MnSO4·H2O was used as metal source.
► We have also proposed a plausible formation mechanism based on experimental evidence, analyses and previous reports.
► Optical property of the material has also been discussed in the present article.