Hydrothermal synthesis of Co-doped In2S3 micropompons and their physical properties

In2−xCoxS3 (x = 0 to 0.1) micropompons (diameters ∼3–4 μm) consisting of ∼10–15-nm-thick randomly self-assembled nanoflakes were synthesized hydrothermally. X-ray study indicated a steady variation of lattice parameter ratio up to 5% Co. Detailed investigations of the Co incorporation in In2S3 were carried out by optical absorbance, room temperature photoluminescence (PL), and electron paramagnetic resonance (EPR) studies. Significant blue shift in the absorbance spectra was noticed due to the crystal-field splitting of Co2+ ions in the host lattice structure. Unlike the visible emission found in undoped In2S3, PL spectra of the Co-doped samples were recognized by a strong ultraviolet emission peak at ∼335 nm, introduced by the t2g level of Co2+ ions, with maximum intensity for 5% Co. Room-temperature and low-temperature EPR spectra revealed octet paramagnetic bands up to 5% Co beyond which a single resonance band appeared.