Color tunability imparted by multi-peak emissions of Eu³⁺ in fluoride-phosphate phosphors

Miscible-order NaGdF₄ fluoride-phosphate phosphor has been synthesized based on tin-fluorophosphate glass with low-melting-point, retaining excellent luminescence property of fluoride nanoparticles. Multi-peak emissions from metastable ⁵D_J (J = 0, 1, 2 and 3) levels are released effectively in the Eu³⁺ doped fluoride nanoparticles, which lifetimes are at the order of millisecond and quantum efficiency at ⁵D₀ level in high Eu³⁺ concentration still remains 88.9%. On the basis of multi-peak emissions from Eu³⁺ and wide-band blue framework from Sn²⁺, the color coordinates of the fluoride-phosphate phosphors are regulated to the white light region and the color rendering index reaches up to 88. Tunable color and high color rendering index make fluoride-phosphate phosphor become a potential candidate for high-quality white light source.