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

Abstract

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 6H15/2 → 4I9/2 + 4G9/2, 6P7/2, 4I11/2, 4F7/2, 4G11/2, 4I15/2, 4F9/2, and 6F3/2 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 $$^{4}{{\text{F}}_{{\raise0.5ex\hbox{$\scriptstyle 9$}\kern-0.1em/\kern-0.15em\lower0.25ex\hbox{$\scriptstyle 2$}}}}\, \to {\,^6}{{\text{H}}_{{\raise0.5ex\hbox{$\scriptstyle {15}$}\kern-0.1em/\kern-0.15em\lower0.25ex\hbox{$\scriptstyle 2$}}}}$$ (blue) and $$^{4}{{\text{F}}_{{\raise0.5ex\hbox{$\scriptstyle 9$}\kern-0.1em/\kern-0.15em\lower0.25ex\hbox{$\scriptstyle 2$}}}}\, \to {\,^4}{{\text{H}}_{{\raise0.5ex\hbox{$\scriptstyle {13}$}\kern-0.1em/\kern-0.15em\lower0.25ex\hbox{$\scriptstyle 2$}}}}$$ (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.