Blue and green emissions with high color purity from nanocrystalline Ca 2Gd 8Si 6O 26:Ln (Ln = Tm or Er) phosphors

Abstract

Blue and green light emissive nanocrystalline Ca 2Gd 8Si 6O 26 (CGS):Tm 3+ and CGS:Er 3+ phosphors with high color purity were prepared by solvothermal reaction method. The structural and morphological properties of these phosphors were evaluated by the powder X-ray diffraction (XRD) and scanning electron microscopy, respectively. From the XRD results, Tm 3+:CGS and Er 3+:CGS phosphors had the characteristic peaks of oxyapatite in the hexagonal lattice structure. The visible luminescence properties of phosphors were obtained by ultraviolet (UV) or near-UV light and low voltage electron beam (0.5–5 kV) excitation. The photoluminescence and cathodoluminescence properties were investigated by changing the variation of Tm 3+ or Er 3+ concentrations and the acceleration voltage, respectively. The CGS:Tm 3+ phosphors exhibited the blue emission due to 1D 2→ 3F 4 transition, while the CGS:Er 3+ phosphors showed the green emission due to 4S 3/2→ 4I 15/2 transition. The color purity and chromaticity coordinates of the fabricated phosphors are comparable to or better than those of standard phosphors for lighting or imaging devices.