Photoluminescent enhancement with co-doped alkali metals in Gd₂O₃:Eu synthesized by co-precipitation method and Judd Ofelt analysis

A series of europium and alkali metal ions (Li⁺, Na⁺ and K⁺)co-doped Gd₂O₃ phosphors were synthesized by the co-precipitation method. The Gd₂O₃ phosphors were synthesized by calcination of the precursors at 800 ℃ for 4 h. The structural, morphological and optical properties of as-synthesized samples were characterized by X-ray diffraction, field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray analysis (EDX), UV-visible spectroscopy, Fourier transform Infrared spectroscopy (FT-IR)and Photoluminescence (PL)techniques. The phase formation was further confirmed by Rietveld refinement. The as-synthesized phosphors were excited under UV radiation at 250 nm and the emission was observed at 612 nm which is a characteristic transition of Eu³⁺ ions corresponding to ⁵D₀ to ⁷F₂ transition. The quenching and type of energy mechanisms were studied using Blasse and Dexter's theory. The alkali metal ions were co-doped in Gd₂O₃:4mol%Eu lattice yielding photoluminescent enhancement. The radiative parameters and Judd Ofelt parameters (Ω₂, Ω₄)were observed from the emission spectra. The photometric parameters were analyzed by CIE co-ordinates and color co-ordinated temperature (CCT)values. The as-synthesized phosphors are expected to be promising red component for the white light emitting diodes.