Determination of Optical Band Gap Energy of Wurtzite ZnO: Ce Nanocrystallites

Abstract

Aim: Determination of optical band gap energy of ZnO:Ce nanocrystallite and effect of doping on the optical band gap energy also probed. Materials and Methods: ZnO:Ce nanoparticles are synthesized by Chemical precipitation route using 1 molar solutions of  Zinc Acetate and Sodium Hydroxide at 60°C. Then I molar percentage (1.72 gm) of Cerium oxide is added with the above solution and stirrered well using magnetic stirrer. Four-five drops Tri Ethyl Amine (TEA) are added as capping agent to control agglomeration. The characterization of sample was studied by XRD, FESEM, FTIR.EDAX and TEM. The UV-Vis spectrometer was used to study the Optical properties of nanopowder Results and Discussion: From the XRD techniques the crystallite size of ZnO nanopowder was determined as13.83 nm at 150˚C which increased to 16.13 nm at temperatures 180˚C. FESEM showed nanoparticle of average size 13-50nm and nano clusters have size of 1µm.  EDAX data is found as Zinc oxide with 99.4% and Cerium 0.6%.TEM confirm the formation ZnO:Ce nanoparticle and it has an average size about 25nm, Some nanorods with average diameter of 40 nm and length of about 290 nm were also observed. The UV absorption spectra for bulk ZnO, nanoparticles of ZnO displayed excitonic peaks at 375 nm and 369 nm respectively. The present study found absorption edge at 372 nm for ZnO:Ce nanoparticle. Conclusion: The UV Absorption spectra showed red shift towards 372 nm due to doping with Cerium and blue shifted relative to Bulk ZnO. From the absorption spectra optical band gap is determined as 3.32 eV. It was found that energy band gap Eg decreases with doping of Ce. The analysis of optical properties shows that ZnO:Ce is promising dielectric material and has potential application in optoelectronic devices .