Pechini synthesis of lanthanide (Eu³⁺/Tb³⁺or Dy³⁺) ions activated BaGd₂O₄ nanostructured phosphors: An approach for tunable emissions

Trivalent lanthanide (Eu³⁺, Tb³⁺ and Dy³⁺) ions activated tunable color emitting BaGd₂O₄ (BG) phosphors were synthesized by a facile Pechini-type sol-gel process. The X-ray diffraction pattern confirmed the orthorhombic phase after annealing at 1300 °C for 5 h. Morphological studies were performed based on the analysis of transmission electron microscopy images, which showed needle type nanorods. The BG phosphor exhibited good photoluminescence (PL) properties in the respective regions when doped with Eu³⁺, Tb³⁺ and Dy³⁺ ions. The Eu³⁺ co-activated BG:Tb³⁺ phosphor yielded tunable emissions including tri-band established white light emission based on the co-activator concentration and excitation wavelength. The energy transfer from Tb³⁺ to Eu³⁺ ions was controlled by selecting a suitable excitation wavelength and the decay measurements were carried out for analyzing the energy transfer efficiency. The cathodoluminescence properties of these phosphors were almost similar to PL properties when doped with individual Eu³⁺, Tb³⁺, and Dy³⁺ ions, but were different when co-doped with Eu³⁺/Tb³⁺ or Eu³⁺/Dy³⁺ ions. In the case of Eu³⁺/Tb³⁺ doped samples, the energy transfer process occurred unlike the PL channel. The calculated Commission International de l’Eclairage chromaticity coordinates of individual ion doped BG phosphors confirmed red, green, and white emissions and for co-doped samples they showed tunable emission.