Synthesis and Luminescent Modulation of ZnS Crystallite by a Hydrothermal Method

Pure and Eu³⁺-doped zinc sulfide (ZnS) crystallites were synthesized through a hydrothermal method using water and ethanol (W/E) as the solvent. The powder samples have been characterized systematically using a number of characterization techniques such as X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy, photoluminescence spectroscopy, and UV–vis absorption spectroscopy. The band gap of ZnS and ZnS/xEu³⁺ was calculated according to absorption spectroscopy, and an obvious red shift with the increasing molar fraction of Eu³⁺-doped ions was found. The luminescent mechanism of ZnS was explored by measuring the emission spectra of ZnS with different ratios of Zn and S. The emission spectra of ZnS/xEu³⁺ included the characteristic emission peak of ZnS and Eu³⁺ ions. The CIE chromaticity coordinates of the ZnS/xEu³⁺ sample varied with the molar fraction of Eu³⁺ ions. The emission intensity and morphology changed with the ratio of W/E in the process of hydrothermal reaction. The results indicate that the luminescence of the ZnS crystallite can be modulated by doping a certain amount of Eu³⁺ ions, changing the ratio of Zn and S, or adding moderate ethanol as the reaction medium.