Effect Of Li-Co- Doping On The Structure And Optical Properties Of Sm3+ Doped PVP Capped Mgal2o4 Nanophosphors

Abstract

In this study, rare earth ion (Sm3+) doped and Li-co-doped magnesium aluminate (MgAl2O4) nanoparticles were synthesized using polymerised sol-gel combustion method. A series of trivalent Samarium (Sm3+) activated magnesium aluminate nanophosphors (Mg1-xSmxAl2O4 (x = 0.02, 0.04, 0.06, 0.08 and 0.10)) and Li-co-doped MgAl2O4: Sm3+nanophosphors were synthesized and their structural, optical and luminescence properties were studied using different characterization techniques such as X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), Diffuse reflectance spectra (DRS), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectroscopy.The polymer used was polyvinylpyrrolidone(PVP) which acted as a reducing agent and stabilizing agent during synthesis. The average crystallite size,which was estimated from the x-ray diffraction analysis of all prepared nanophosphors,was around 10 nm. FTIR spectra showed various fingerprint bands in the range 400-700 cm-1. DRS spectra showed strong absorption in the UV region at 401 nm.XPS analysis confirmed the presence of different elements in the prepared nanophosphors. Photoluminescence emission spectra showed many characteristic peaks in the visible region for all samples upon 401 nm excitation. The most prominent peak was at 649 nm wavelength corresponding to the 4G5/2 – 6H9/2 transition. Li-co-doping enhances the emission intensity by almost 1.98 % without change in the peak positions. The results suggest that the synthesized nanophosphors could be an excellent choice for orange-red emitting luminescent materials for UV-excited phosphor-converted white light-emitting diodes and for various photonic applications.