The Dependence on Temperature of the Mn⁴⁺ Emission Intensity and Lifetime in Na₂SiF₆

We have measured the dependence of the Mn⁴⁺ lifetime and intensity on temperature of commercial Na₂SiF₆:Mn⁴⁺ phosphor. The data are fitted to existing physical models to extract the activation energy for thermal quenching. The parameters of our fitting are compared with those reported for laboratory synthesized Na₂SiF₆:Mn⁴⁺ and commercial K₂SiF₆:Mn⁴⁺ phosphors that is sold under the trade name, TriGain®. This comparative analysis sheds light on the mechanism of thermal quenching of the Mn⁴⁺ ion luminescence in M₂SiF₆ (M = K, Na) compounds. We show that the activation energy and the onset temperature of thermal quenching for the ²E→⁴T₂→⁴A₂ crossover process is correlated with the energy of the ⁴T₂ level and argue that this is a robust electronic structure-property relationship in fluoride hosts with low defect density. The study provides, therefore, an understanding of the factors responsible for non-radiative relaxation processes, which is fundamental to the understanding of phosphor quantum efficiency and performance.