The luminescence behavior of Eu^(3+)-activated lanthanum tungstate nanophosphors exhibiting intense red emission was systematically explored by modifying their surfaces using various agents,including polyvinylpyrrolid...The luminescence behavior of Eu^(3+)-activated lanthanum tungstate nanophosphors exhibiting intense red emission was systematically explored by modifying their surfaces using various agents,including polyvinylpyrrolidone(PVP),cetyltrimethylammonium bromide(CTAB),trisodium citrate(TC),polyvinyl alcohol(PVA),and ethylene glycol(EG).These nanophosphors were synthesized via a facile hydrothermal-assisted solid-state reaction.X-ray diffraction(XRD)analysis confirmed the orthorhombic crystal structure of all the prepared samples.Morphological and size analyses were performed using scanning electron microscopy(SEM)and particle size distribution profiling.High-resolution transmission electron microscopy(HRTEM)complemented by elemental mapping was used to evaluate the particle dimensions and interplanar spacing of the optimized sample.Fourier-transform infrared spectroscopy(FTIR)was used to identify functional groups and assign corresponding vibrational bands.X-ray photoelectron spectroscopy(XPS)provided insights into the elemental composition and binding energies of the optimized nanophosphors.Notably,the PVA-modified sample doped with 14mol%Eu3+exhibited pronounced red emission at 616 nm,attributed to the ^(5)D_(0)→^(7)F_(2) electric dipole transition of Eu3+ions under ultraviolet(UV)excitation.Detailed excitation and emission spectral analyses were performed,with band assignments corresponding to the relevant electronic transitions.Among the surface-treated variants,the PVA-modified nanophosphors demonstrated exceptional color purity of 99.6%,international commission on illumination(CIE)chromaticity coordinates of(0.6351,0.3644),and a correlated color temperature of 1147 K.These superior optical features are ascribed to the enhanced surface passivation and suppression of nonradiative recombination,facilitated effectively by the PVA surface layer.Lifetime decay analysis across all samples revealed a significantly extended lifetime for the optimized composition,further supporting its superior luminescence efficiency.In addition,evaluation of the biocompatibility of the nano-phosphors highlighted their potential for biomedical applications.Overall,these findings emphasize the efficacy of PVA-modified Eu^(3+)-doped lanthanum tungstate nanophosphors as highly efficient red emitters,suitable for application in white light-emitting diodes(WLEDs)and latent fingerprint detection while offering valuable insights into the role of surface modification in tuning the optical properties of nanophosphors.展开更多
Eu3＋ doped strontium-aluminium-bismuth-borate glasses with the chemical composition（50–x）B2O3＋20Bi2O3＋7Al F3＋ 8Sr O＋15Sr F2＋x Eu2O3（where x=0.1 mol.%, 0.5 mol.%, 1.0 mol.% and 1.5 mol.%） were prepared by th...Eu3＋ doped strontium-aluminium-bismuth-borate glasses with the chemical composition（50–x）B2O3＋20Bi2O3＋7Al F3＋ 8Sr O＋15Sr F2＋x Eu2O3（where x=0.1 mol.%, 0.5 mol.%, 1.0 mol.% and 1.5 mol.%） were prepared by the conventional melt quenching technique.Structural properties of the prepared glasses were analysed through X-ray diffraction（XRD）, scanning electron microscopy（SEM）, energy dispersive spectroscopy（EDS） and Raman spectral techniques.Thermal stability of glass was analysed by differential thermal analysis（DTA） curve.Photoluminescence characteristics were studied using excitation, emission spectra and decay curves of Eu3＋ doped strontium-aluminium-bismuth-borate glasses.The Judd-Ofelt（J-O） intensity parameters, Ωλ（λ=2, 4 and 6） were obtained using emission spectra and was used to identify the nature of Eu3＋ ions with their surrounding ligands.Using J-O parameters the transition probabilities（A）, stimulated emission cross-sections σE p, branching ratios（βR） and radiative lifetimes（τmeas and τcal） were evaluated for the 5D0→7F J（J=0, 1, 2, 3 and 4） transition of Eu3＋ ions in the present glasses.The decay profiles were found to be non exponential for all the concentrations and the measured lifetimes（τmeas） were obtained from the decay profiles.The higher values of A, σE p, βR and quantum efficiency（η） for 5D0→7F2 emission transition at 617 nm confirmed the present glass was as active medium for red laser emission applications.展开更多
基金financial support provided by the National Research Foundation of Korea(NRF)through the Basic Science Research Program,funded by the Ministry of Education(Nos.2021R1A6A1A03039493 and 2022R1A2C1009389)the authors extend their appreciation to the Researchers Supporting Project(No.RSPD2025R956)。
文摘The luminescence behavior of Eu^(3+)-activated lanthanum tungstate nanophosphors exhibiting intense red emission was systematically explored by modifying their surfaces using various agents,including polyvinylpyrrolidone(PVP),cetyltrimethylammonium bromide(CTAB),trisodium citrate(TC),polyvinyl alcohol(PVA),and ethylene glycol(EG).These nanophosphors were synthesized via a facile hydrothermal-assisted solid-state reaction.X-ray diffraction(XRD)analysis confirmed the orthorhombic crystal structure of all the prepared samples.Morphological and size analyses were performed using scanning electron microscopy(SEM)and particle size distribution profiling.High-resolution transmission electron microscopy(HRTEM)complemented by elemental mapping was used to evaluate the particle dimensions and interplanar spacing of the optimized sample.Fourier-transform infrared spectroscopy(FTIR)was used to identify functional groups and assign corresponding vibrational bands.X-ray photoelectron spectroscopy(XPS)provided insights into the elemental composition and binding energies of the optimized nanophosphors.Notably,the PVA-modified sample doped with 14mol%Eu3+exhibited pronounced red emission at 616 nm,attributed to the ^(5)D_(0)→^(7)F_(2) electric dipole transition of Eu3+ions under ultraviolet(UV)excitation.Detailed excitation and emission spectral analyses were performed,with band assignments corresponding to the relevant electronic transitions.Among the surface-treated variants,the PVA-modified nanophosphors demonstrated exceptional color purity of 99.6%,international commission on illumination(CIE)chromaticity coordinates of(0.6351,0.3644),and a correlated color temperature of 1147 K.These superior optical features are ascribed to the enhanced surface passivation and suppression of nonradiative recombination,facilitated effectively by the PVA surface layer.Lifetime decay analysis across all samples revealed a significantly extended lifetime for the optimized composition,further supporting its superior luminescence efficiency.In addition,evaluation of the biocompatibility of the nano-phosphors highlighted their potential for biomedical applications.Overall,these findings emphasize the efficacy of PVA-modified Eu^(3+)-doped lanthanum tungstate nanophosphors as highly efficient red emitters,suitable for application in white light-emitting diodes(WLEDs)and latent fingerprint detection while offering valuable insights into the role of surface modification in tuning the optical properties of nanophosphors.
基金University Grants Commission (UGC) for providing the financial assistance in the form of major research project (No.F.40-443/2011 (SR)
文摘Eu3＋ doped strontium-aluminium-bismuth-borate glasses with the chemical composition（50–x）B2O3＋20Bi2O3＋7Al F3＋ 8Sr O＋15Sr F2＋x Eu2O3（where x=0.1 mol.%, 0.5 mol.%, 1.0 mol.% and 1.5 mol.%） were prepared by the conventional melt quenching technique.Structural properties of the prepared glasses were analysed through X-ray diffraction（XRD）, scanning electron microscopy（SEM）, energy dispersive spectroscopy（EDS） and Raman spectral techniques.Thermal stability of glass was analysed by differential thermal analysis（DTA） curve.Photoluminescence characteristics were studied using excitation, emission spectra and decay curves of Eu3＋ doped strontium-aluminium-bismuth-borate glasses.The Judd-Ofelt（J-O） intensity parameters, Ωλ（λ=2, 4 and 6） were obtained using emission spectra and was used to identify the nature of Eu3＋ ions with their surrounding ligands.Using J-O parameters the transition probabilities（A）, stimulated emission cross-sections σE p, branching ratios（βR） and radiative lifetimes（τmeas and τcal） were evaluated for the 5D0→7F J（J=0, 1, 2, 3 and 4） transition of Eu3＋ ions in the present glasses.The decay profiles were found to be non exponential for all the concentrations and the measured lifetimes（τmeas） were obtained from the decay profiles.The higher values of A, σE p, βR and quantum efficiency（η） for 5D0→7F2 emission transition at 617 nm confirmed the present glass was as active medium for red laser emission applications.
