Cathodoluminescence properties of SiO2:Pr3+and ZnO.SiO2:Pr3+ phosphor nanopowders

Abstract

The successful incorporation of ZnO nanoparticles in Pr3+-doped SiO2 using a sol–gel process is reported. SiO2:Pr3+ gels, with or without ZnO nanoparticles, were dried at room temperature and annealed at 600 °C. On the basis of the X-ray Diffraction (XRD) results, the SiO2 was amorphous regardless of the incorporation of Pr3+ and nanocrystalline ZnO or annealing at 600 °C. The particles were mostly spherical and agglomerated as confirmed by Field Emission Scanning Electron Microscopy. Thermogravimetric analysis of dried gels performed in an N2 atmosphere indicated that stable phases were formed at ≥900 °C. Absorption bands ascribed to 3H4-3P(J = 0,1,2), 1I6 and 1D2 in the UV–VIS region were observed from SiO2:Pr3+ colloids. The red cathodoluminescent (CL) emission corresponding to the 3P0 → 3H6 transition of Pr3+ was observed at 614 nm from dried and annealed SiO2:Pr3+ powder samples. This emission was increased considerably when ZnO nanoparticles were incorporated. The CL intensity was measured at an accelerating voltage of 1-5 keV and a fixed beam current of 8.5 μA. The effects of accelerating voltage on the CL intensity and the CL degradation of SiO2:Pr3+ and ZnO·SiO2:Pr3+were also investigated using Auger electron spectroscopy coupled with an Ocean Optics S2000 spectrometer.