Loading...

Fast two-step microwave-activated synthesis of Mn doped ZnS nanocrystals: Comparison of the luminescence and doping process with thermochemical approach

Marandi, M ; Sharif University of Technology | 2011

1263 Viewed
  1. Type of Document: Article
  2. DOI: 10.1016/j.jlumin.2010.11.025
  3. Publisher: 2011
  4. Abstract:
  5. In this work we report a fast two-step microwave activated synthesis of the ZnS:Mn nanocrystals. Zn(NO3)2 and Na2S 2O3 were used as the precursors and Mn(NO 3)2 was employed as the source of the impurity. The aqueous synthesis was based on the heat sensitivity of Na2S 2O3, which releases some S species on heating. Consequently, the reaction was well activated under microwave irradiation resulting in formation of ZnS:Mn nanocrystals. Thioglycerol (TG) was also used as the capping agent and the catalyst of the reaction. The synthesis process was done in two steps, i.e. 1 min irradiation without TG and then injection of TG and continuation of irradiation. ZnS:Mn nanocrystals were quickly formed in the solution and luminescence was emerged in a few minutes. Optical transmission spectroscopy and X-ray diffraction analysis demonstrated formation of ZnS:Mn nanocrystals with a cubic crystalline structure and 3.0 nm average size. Photoluminescence measurements also showed some spectra with a Mn related peak located at 585 nm. The mentioned peak corresponds to 4T 1→6A1 transition in Mn impurities and revealed the effective incorporation of Mn ions inside the nanocrystals. Evolution of the PL was also investigated and showed an increase in longer irradiation times. A qualitative model is also used to justify the necessity of using a two-step method as well as the PL emergence and increase in longer irradiation times. The model is based on separation between the nucleation and growth steps and significant role of TG in these stages. Finally, we present a comparison between the results of microwave activated method and two-step thermochemical approach. Although the synthesis time in microwave activated method was considerably short (less than 5 min), the luminescence properties were quite comparable with long time thermochemical approach. The doping process was also investigated for different Mn/Zn concentrations in two approaches. The results demonstrated that the doping occurred more effectively in the microwave activated synthesis
  6. Keywords:
  7. Aqueous synthesis ; Average size ; Capping agent ; Cubic crystalline ; Doping ; Doping process ; Heat sensitivity ; Luminescence properties ; Microwave synthesis ; Mn doped ZnS ; Mn impurity ; Mn ions ; Nucleation and growth ; Optical transmission spectroscopy ; Photoluminescence measurements ; Qualitative model ; Synthesis process ; Synthesis time ; Thioglycerol ; Two step method ; ZnS:Mn ; Doping (additives) ; Impurities ; Irradiation ; Light transmission ; Manganese ; Nanocrystals ; Photoluminescence ; Synthesis (chemical) ; X ray diffraction ; X ray diffraction analysis ; Zinc sulfide ; Microwave irradiation
  8. Source: Journal of Luminescence ; Volume 131, Issue 4 , April , 2011 , Pages 721-726 ; 00222313 (ISSN)
  9. URL: http://www.sciencedirect.com/science/article/pii/S0022231310005089