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.