Korean Journal of Materials Research ISSN:1225-0562(Print) 2287-7258(Online) 한국재료학회지

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 ⁴F_9/2→ ⁶H1_3/2 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 ⁴F_9/2→ 6H15/2 and ⁴F_9/2→ ⁶H1_3/2 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.