Structural, morphological and optical properties of Eu-N co-doped zinc oxide nanoparticles synthesized using co-precipitation technique

The doping of metal oxides with rare-earth element is an effective way of enhancing the optical properties of ZnO nanoparticles. The ZnO nanoparticles were prepared using co-precipitation method with different concentrations of Eu, constant N doping and characterized through X-ray diffraction, scanning electron microscopy, Raman spectroscopy and UV-visible spectroscopy. The Rietveld refined XRD of ZnO nanoparticles confirms the hexagonal wurtzite structure. The XRD results indicated that crystallite size increases with doping and found in the range of 37-52 nm. Scanning electron microscopy illustrated that ZnO nanoparticles were less agglomerated and the average size of nanoparticles was found to increase from 62 to 90 nm with doping. Raman spectrum also confirmed hexagonal wurtzite arrangement of all samples. The band gap of pristine ZnO nanoparticles was found 3.18 eV as confirmed by UV-visible spectroscopy. The red shift (3.14 eV & 3.16 eV) in band gap was observed at 2 & 3 mol% of Eu, while blue shift (3.20 eV & 3.23 eV) in band gap was observed at 1 & 4 mol% of Eu respectively. This modification in the band gap makes ZnO nanoparticles an appropriate electrode material for dye-sensitized solar cells and optoelectronic devices.