Electron beam induced green luminescence and degradation study of CaS:Ce nanocrystalline phosphors for FED applications |
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Authors: | Vinay Kumar Varun Mishra I.M. Nagpure J.J. Terblans |
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Affiliation: | a Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein 9300, South Africa b Department of Physics, Lovely Professional University, Phagwara 144 402, Punjab, India |
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Abstract: | Green luminescence and degradation of Ce3+ doped CaS nanocrystalline phosphors were studied with a 2 keV, 10 μA electron beam in an O2 environment. The nanophosphors were synthesized by the co-precipitation method. The samples were characterized using X-ray diffraction, Transmission electron microscopy, Scanning electron microscopy/electron dispersive X-ray spectroscopy and Photoluminescence (PL) spectroscopy. Cubic CaS with an average particle size of 42 ± 2 nm was obtained. PL emission was observed at 507 nm and a shoulder at 560 nm with an excitation wavelength of 460 nm. Auger electron spectroscopy and Cathodoluminescence (CL) were used to monitor the changes in the surface composition of the CaS:Ce3+ nanocrystalline phosphors during electron bombardment in an O2 environment. The effect of different oxygen pressures ranging from 1 × 10−8 to 1 × 10−6 Torr on the CL intensity was also investigated. A CaSO4 layer was observed on the surface after the electron beam degradation. The CL intensity was found to decrease up to 30% of its original intensity at 1 × 10−6 Torr oxygen pressure after an electron dose of 50 C/cm2. The formation of oxygen defects during electron bombardment may also be responsible for the decrease in CL intensity. |
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Keywords: | Surface reaction Degradation Nanophosphors ESSCR |
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