Synthesis characterization and optical properties study of zns zns mn zns ni nano structured materials

Abstract

newline Abstract newlinePage 1 newlineAbstract newlineZnS, ZnS:Mn, ZnS:Ni nano-crystals were successfully synthesized at newlinedifferent weight percentage into poly-vinyl alcohol matrix by chemical route method. newlineThe influence of different dopant concentrations on the formation of surface newlinemorphology, particle size and optical properties of both undoped and doped ZnS nanocrystalline newlinecompounds were investigated. The nano structure was characterized with the newlinehelp of X-ray diffraction (XRD). XRD studies confirmed that the nano crystalline newlinecompounds formed were zinc blende. Using Debye Scherrer s formula, the crystal size newlineof ZnS, ZnS:Mn, ZnS:Ni nanoparticles were calculated and the average particle were newlinefound to be 2.88 nm, 2.27 nm, 2.49 nm respectively. However, the broadening of the newlineXRD peaks at different weight percentage of Mn and Ni indicates the presence of both newlineMn and Ni. With the increase of dopant concentration, the particle size decreases and newlineband gap energy increases. Transmission Electron Microscopy (TEM) showed the newlineuniformity of the nanoparticles and their size. The particles were found to be spherical newlinein shape and the average particle size for ZnS, ZnS:Mn, ZnS:Ni obtained from TEM newlinewere 3.5 nm, 2.45 nm, 3.75 nm respectively. Selected area electron diffraction (SAED) newlineshowed a set of three well defined rings corresponding to planes (111), (220), (311) newlinewhich tallied well with the JCPDS card No. 05-0566. Surface morphology newlinewas studied with the help of Scanning Electron Microscopy (SEM). The compositional newlineanalysis of ZnS:Mn and ZnS-Ni were carried out by EDX spectrum confirms the doping newlinepercentage of Mn and Ni in ZnS nanoparticles. The EDX spectra for Mn and Ni doping newlineat 0.25%, 0.50% 0.75%, 1.0%, also confirm the presence of Mn and Ni in ZnS. The PL newlinestudy indicates that both Mn and Ni act as electron trapping centres and this results newlineAbstract newlinePage 2 newlinenonradiative recombination and hence the luminescence intensities decreases because of newlineS-2. The band gap energy was calculated from the absorption spectra using Double newlineBeam Automated Spectrophotometer (Hitachi U3210) [UV-Visible spectrometer] and newlineband gap was found higher than bulk ZnS. The absorbance peaks for ZnS:Mn and newlineZnS:Ni showed a tendency towards blue shift. It is also observed that with the newlineincrease of doping concentration, the band gap increases. The particle size obtained newlinefrom XRD, TEM and Brus equation are nearly equal at different concentration for both newlineMn and Ni. Raman spectra indicated ZnS in well crystalline state both for Mn and Ni newlinedoping. The 0.25% doping percentage is more effective in respect of particle size for newlineboth Mn and Ni which is one of the fundamental requirement in nanoparticles. Blue and newlinegreen emission at 0.5% to 1.0% indicate large band gap which has industrial newlineapplication. More broadening of PL peaks for ZnS:Mn has been observed than ZnS:Ni.