Effect of excitation wavelength and europium doping on the optical properties of nanoscale zinc oxide
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Effect of excitation wavelength and europium doping on the optical properties of nanoscale zinc oxide Ishan Choudhary1,* 1 2
, Ravi Shukla2, Arvind Sharma1, and K. K. Raina2
Chandigarh Engineering College, Landran, Mohali, Punjab 140307, India Advanced Functional Smart Materials Laboratory, Department of Physics, DIT University, Dehradun, Uttarakhand 248009, India
Received: 21 June 2020
ABSTRACT
Accepted: 20 September 2020
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 5D0?7F1 and 5D0?7F2 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 D0?7F2 transitions are taking place. The intensity ratio of 5D0?7F2 / 5D0?7F1 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.
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Springer Science+Business
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https://doi.org/10.1007/s10854-020-04525-x
J Mater Sci: Mater Electron
1 Introduction The modern-day electronic industry has been revolutionized from the past few years, mainly in delivering the products which have high performance, high reliability, light-weight, flexible, low-cost processing, and smaller size [1–4]. Metal oxide-based semiconductors have emerged out to be the most suitable candidate for this purpose due to its ease of processing, low-cost fabrication, and solution processability [5–10]. Furthermore, due to the quantum size effect at the nanoscale, these oxides illustrate exciting properties such as wide window for bandgap, superior surface properties, improved sensing ability, and enh
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