White-light-emitting Dy3+-doped amorphous SiO2 nanophosphors derived from rice husk

This research reports on the synthesis and characterization of white-light-emitting rice husk nano-silica doped with dysprosium ion (SiO2:Dy3+). The synthesis was carried out via the sol-gel method. Scanning electron microscopy and transmission electron microscopy show agglomerated particles. X-ray diffraction analysis shows all samples have amorphous structure. Diffuse reflectance analysis shows absorption band of the host SiO2 and H-6(15/2) -> I-4(9/2) + (4)G(9/2), P-6(7/2), I-4(11/2), F-4(7/2), (4)G(11/2), I-4(15/2), F-4(9/2), and F-6(3/2) transitions of Dy3+ ions. Photoluminescence excitation spectra of the nanophosphors display both the host band as well as the intra-configurational transition lines of Dy3+ in the 250-500-nm range. Photoluminescence emission obtained at 275- and 350-nm excitation wavelengths shows two dominant emission lines assigned to the F-4(9/2) -> H-6(15/2) (blue) and F-4(9/2) -> H-4(13/2) (yellow) transitions of the Dy3+ ion. The International Commission on Illumination (CIE) chromaticity coordinate diagrams display white light with correlated color temperature (CCT) between 4868 and 6256 K (cold white light). These results show that SiO2:Dy3+ derived from rice husk has the potential for applications in white-light-emitting diodes (WLEDS) and other lighting technologies.