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pp.339-344
A series of CaNb2O6:Dy3+, CaNb2O6:Eu3+ and CaNb2O6:Dy3+, Eu3+ phosphors were prepared by solid-state reaction process. The effects of activator ions on the structural, morphological and optical properties of the phosphor particles were investigated. XRD patterns showed that all the phosphors had an orthorhombic system with a main (131) diffraction peak. For the Dy3+-doped CaNb2O6 phosphor powders, the excitation spectra consisted of one broad band centered at 267 nm in the range of 210-310 nm and three weak peaks; the main emission band showed an intense yellow band at 575 nm that corresponded to the 4F9/2→ 6H13/2 transition of Dy3+ ions. For the Eu3+-doped CaNb2O6 phosphor, the emission spectra under ultraviolet excitation at 263 nm exhibited one strong reddish-orange band centered at 612 nm and four weak bands at 536, 593, 650, and 705 nm. For the Dy3+ and Eu3+-codoped CaNb2O6 phosphor powders, blue and yellow emission bands due to the 4F9/2→ 6H15/2 and 4F9/2→ 6H13/2 transitions of Dy3+ ions and a main reddish-orange emission line at 612 nm resulting from the 5D0→ 7F2 transition of Eu3+ ions were observed. As the concentration of Eu3+ ions increased from 1 mol% to 10 mol%, the intensities of the emissions due to Dy3+ ions rapidly decreased, while those of the emission bands originating from the Eu3+ ions gradually increased, reached maxima at 10 mol%, and then slightly decreased at 15 mol% of Eu3+. These results indicate that white light emission can be achieved by modulating the concentrations of the Eu3+ ions incorporated into the Dy3+-doped CaNb2O6 host lattice.
