Synthesis And Characterization Of Doped ZnS Nano Luminescent Materials

Nanoscience has drawn considerable interest and has been investigated all over the world. The nanoparticles have different properties compared with its bulk such as quantum size effect, surface effect, the dielectric confinement effects, and etc. The intrinsic optical properties of nanoparticles have been thoroughly studied and the optical properties of semiconductor nanoparticles doped with activator elements such as ZnS:Mn2+ which was first prepared in 1993 led to a new stage of investigation of optical properties of nanoparticles. In this thesis, we studied opticalproperties of ZnS nanocrystallites doped with M ( Cu2+, Cu+ or Mn2+). The new results are as follows.(1) By sol-gel method, green-light emitting ZnS:Cu nanoparticles surface-capped by Na2S2O3 were obtained. During the synthesis process, Na5P3O10 were used as protecting reagent in order to increase the stability and dispersivity of nanoparticles in organic collosol. We also studied the factors that affect the synthesis such as doping concentration, Na2S2O3 dosage, pH and so on, and found the optimal technical reaction conditions. The photoluminescence (PL) spectra, XRD spectra and UV-vis spectra were measured to characterize their optical properties and crystal structures.(2) By sol-gel method, M ( Cu2+ and Mn2+ ) were directly doped into ZnS and two kinds of ZnS matrix white-light emitting nanoparticles were obtained. One kind is only doped with Mn2+ and the other is doped with both of Cu2+ and Mn2+. The ZnS:M nanoparticles were surface-capped by methacrylic acid. The photoluminescence (PL) spectra, XRD spectra and UV-vis spectrawere measured to characterize their optical properties and crystal structures.(3) The average diameter of the prepared ZnS:Mn particles is 7nm. Its photoluminescence (PL) spectrum exhibits two emission peaks under irradiation, one is at 480nm with a blue-light emitting originating from the ZnS matrix and the other is at 590 nm with a yellow-light emitting originating from the doping Mn2+. In general, the two violent emittings come into being a white-light emitting.(4) The average diameter of the prepared ZnS:Mn,Cu particles is also 7nm. Its photoluminescence (PL) spectrum also exhibits two emission peaks under irradiation, one is at 480nm with a blue-light emitting and the other is at 600 nm with a yellow-light emitting. In general, the two violent emittings come into being a white-light emitting.