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Dy-doped and Dy/Eu-codoped GdMoO phosphors were synthesized by hydrothermal method. The results of X-ray diffraction indicate that the GdMoO phosphors have crystallized with the monoclinic structure. The emission spectra exhibit emissions at 577 nm and 488 nm that corresponded to the yellow and blue emissions, respectively. The emission intensity of these bands increases with the rise of the Dy up to a particular concentration and then reduces at a higher level. The observed behaviour was explained on the basis of concentration quenching phenomena. The enhancement in the emission intensity of the Dy with the addition of Eu along with the red emission at 617 nm for Eu was noted. The energy transfer between the two rare earth ions was studied. Codoping with the trivalent Eu ions neutralized the red emission part of the phosphor. Thus, by incorporating the adequate quantity of Eu the photometric characteristics of the phosphors can be adjusted. [ABSTRACT FROM AUTHOR]

The photoluminescence (PL) properties of singly doped (Dy3+) and codoped (Dy3+, Eu3+) fluoroaluminoborate glasses, with an emphasis on the white light generation, are studied. The γ-irradiation led to the formation of defects in Dy3+-doped glasses and photoreduction of Eu3+ to Eu2+ in codoped (Dy3+, Eu3+) glasses. The electron paramagnetic resonance spectra confirm the presence of divalent europium ions and defects in Dy3+, Dy3+-Eu3+-doped glasses. The FTIR spectra mainly establish the compaction of glass network due to γ-irradiation. From the PL spectra, the intensity ratio of Dy3+ emission bands yellow to blue (4F9/2-6H13/2/4F9/2-6H15/2) defines the site symmetry, covalency, and feasibility of extracting white light. The existence of an energy transfer (ET) from Dy3+ to Eu3+ ions are established due to the decrease in intensity of Dy3+ peaks with an increase of Eu2O3 content. Moreover, the non-exponential nature of decay curves was well fitted with the generalization of Yokota-Tanimoto model for electric dipole-quadrupole ( S = 8) interaction that is responsible for ET process from sensitizer (Dy3+) to activator (Eu3+). [ABSTRACT FROM AUTHOR]