Hydrothermal preparation of ZnS: Mn quantum dots and the effects of reaction temperature on its structural and optical properties

In this paper, the structural and optical properties of ZnS: Mn (0.6 at.%) quantum dots (QDs) synthesized by hydrothermal method at different reaction temperature were reported. X-ray diffraction patterns indicated that the ZnS: Mn QDs had cubic structure, and the average grain size increased from 3.75 to 6.36 nm with rising reaction temperature. Scanning electron microscope and transmission electron microscopy images revealed that the small grain size made samples poor dispersion. Also, we provided Fourier transform infrared spectroscopy spectra of the ZnS: Mn QDs to investigate components information. Further, optical properties of ZnS: Mn QDs were found to be affected by quantum confinement effect and specific surface area. The optical energy gap increased from 3.2 to 3.5 eV with the decrease of reaction temperature. Moreover, photoluminescence emissions of all samples showed the blue shift of position and the increase of emissions intensity with decreasing reaction temperature.