Color tunable emission and enhance green light emission in oxyfluoride glass ceramics containing Ce³⁺/Tb³⁺: Na₅Y₉F₃₂ nanocrystals

The Oxyfluoride glass ceramics (GCs) containing Na₅Y₉F₃₂:Ce³⁺/Tb³⁺ nanocrystals were synthesized using a high-temperature melting method. The microstructural, luminescent property, energy transfer, and thermal stability of the samples were investigated. Under 310 nm excitation, the co-doped GCs exhibited two emissions at blue 380 nm (Ce³⁺: 5d → 4f) and green 542 nm (Tb³⁺: ⁵D₄ → ⁷F₅). The luminous color can be tuned from blue (0.1966, 0.1512) to yellow–green (0.288, 0.4473) by increasing the content of Tb³⁺ ions. Decay curves revealed efficient energy transfer from Ce³⁺ to Tb³⁺, with an energy transfer efficiency (ETE) of up to 47.54%. According to the theory of Dexter energy transfer, dipole–dipole interaction was confirmed as the mechanism for energy transfer between Ce³⁺ and Tb³⁺. Moreover, the prepared GCs demonstrated good thermal stability even at elevated temperatures. These findings indicate that the Na₅Y₉F₃₂: Ce³⁺/Tb³⁺ GCs can serve as materials for W-LEDs, excited by near-ultraviolet light, to enhance of green light emission.