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8142428 
Journal Article 
Effect of excitation wavelength and europium doping on the optical properties of nanoscale zinc oxide 
Choudhary, I; Shukla, R; Sharma, A; Raina, KK 
2020 
Yes 
Journal of Materials Science: Materials in Electronics
ISSN: 0957-4522
EISSN: 1573-482X 
SPRINGER 
DORDRECHT 
31 
22 
20033-20042 
WOS:000573424200008 
The present study demonstrates a red light-emitting nano-phosphor material tailored by doping europium (Eu+3) ions in zinc oxide (ZnO), prepared using a solution based co-precipitation method. Instead of using acetates or nitrates based precursor for Eu(+3)doping, here we directly used europium oxide (Eu2O3) as a precursor. The precursor showed a limited amount of solubility only up to 3% in an alcoholic solution. No phase change of any kind in x-ray diffraction (XRD) patterns indicates effective Eu(+3)doping in ZnO. Also, the broadening of the XRD peaks confirms the reduction of size to the nanoscale. Further, the optical properties of pure ZnO and Eu+3-doped ZnO are elucidated using UV-Visible and photoluminescence (PL) spectroscopy. A redshift of 10 nm in the absorption edge from pure ZnO to 3% Eu+3-doped ZnO concentration is detected, indicating that Eu(+3)ions occupy impurity trap levels below the conduction band. A regular increase in the excitation wavelength from 190 nm to 270 nm confirms that 226 nm excitation wavelength is the onset point for the emission from Eu(+3)ions. The Eu+3-doped ZnO nanoparticles exhibit two emission peaks at 584 nm and 613 nm corresponding to(5)D(0)->(7)F(1)and(5)D(0)->(7)F(2)transition of Eu(+3)ions at low excitation wavelengths of 254 nm and 270 nm. Out of these two peaks, 613 nm peak was the most intense suggesting that mostly(5)D(0)->(7)F(2)transitions are taking place. The intensity ratio of(5)D(0)-> F-7(2)/D-5(0)->(7)F(1)for both excitation wavelengths of 254 nm and 270 nm is always greater than one confirms the efficient emission of red color from Eu(+3)ions. In addition to that, the samples exhibit a high color purity value of 83.78 %, with CIE coordinates (0.60, 0.40) lying closer to the ideal red color CIE coordinates at an excitation wavelength of 254 nm.