Phosphors and photonic crystals

Zhang, Shuo (2008) Phosphors and photonic crystals. PhD thesis, University of Greenwich.

Abstract

Y2WO6: RE, Y2O2S: RE, Gd2O2S: RE phosphors have been prepared using the urea homogeneous precipitation method and firing. Stokes luminescence properties of Y2WO6: RE excited with a FRED (frequency doubled argon ion) UV laser (257 nm) have been studied. The emissions have been assigned to their corresponding energy levels. Differences in the emission spectra of Y2WO6: RE, Y2O2S: RE, Gd2O2S: RE and Y2O3: RE have been attributed to the different site symmetries of the rare earth ions and to the different phonon energies of the lattices.

Fine nanostructures present within butterfly wing scales have been faithfully replicated using a precursor Y2O3: Eu phosphor solution. Monodisperse polystyrene spheres and SiO2 spheres were synthesised and they were used to synthesise well ordered bare opal templates. Photonic phosphor crystals of Y2O3: Eu, Tb, Gd and Y2O3: Tm were synthesised using these templates to study the photonic band gap properties. Nano-sized Y2O3: Eu phosphors have been successfully incorporated into mono-dispersed silica spheres which have been assembled into photonic crystals. It has been observed that when light-emitting phosphors (e.g. Y2O3: Eu) and dyes (e.g. acid red dye) are incorporated into the opal structures, their emission spectra are modified when the stopbands of the opals overlap the emission bands of the light-emitting materials.

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