Spectral characteristics and luminescence applications of Eu3+-activated fluorosilicate Na2MgGd2[SiO3]4F2

This work reports the luminescence spectra and application of novel Eu³⁺-doped Na₂MgGd₂[SiO₃]₄F₂ phosphor. The X-ray powder diffraction confirmed the pure phase formation of the samples with the monoclinic space group P2₁/c (No:14). The phosphors demonstrated efficient red emission at 613 nm from the electric dipole transitions ⁵D₀→⁷F₂. The optimal doping concentration was found to be approximately 25 mol%. Na₂MgGd₂[SiO₃]₄F₂:0.25Eu³⁺ exhibits a high quantum efficiency (QE) of 57 % with excellent thermal stability and pure chromaticity. Red- and the white light-emitting diode devices were packaged using InGaN chips and Na₂MgGd₂[SiO₃]₄F₂:0.25Eu³⁺. The fabricated WLED has CIE coordinates of (x = 0.33, y = 0.34), which are very close to the white point in the National Television System Committee (x = 0.33, y = 0.33). The color rendering index (CRI, Ra) and correlated color temperature (CCT) of the WLED are 91 and 4400 K, respectively. The results show that as a red luminescent phosphor, it is a potential candidate for the preparation of near-UV/blue InGaN-based WLEDs.