The decay curves of luminescence from Eu2+ in β-SiAlON are effectively analyzed using the general-order kinetics formula

Abstract Defects in phosphors affect not only luminescence intensity but also emission peak width, decay time, and afterglow. The green phosphor β -SiAlON:Eu 2+ exhibits the green emission of Eu 2+ at 520 nm and the blue emission of nitrogen vacancies at 460 nm in time-resolved fluorescence measurements. The decay time of the intrinsic Eu 2+ transition is 0.7 μ s, but afterglow is detected from 50 μ s to 0.01 s. This afterglow decay curve is the same for the green emission of Eu 2+ and the blue emission of nitrogen vacancies, suggesting that the defect levels of the nitrogen vacancies affect the Eu 2+ transition. The afterglow decay curves were analyzed using the formula of the general-order kinetics, 1 + t / τ B − n , where n is the decay power and τ B is the decay time. This equation is generally used when analyzing afterglow on the order of seconds to hours but has not been examined systematically applied in samples with different concentrations of Eu 2+ and temperatures on the order of nanoseconds to milliseconds. The decay power n is approximately 1 for all Eu 2+ concentrations ( x = 0.001–0.3) and undoped β -SiAlON. The decay time τ B is correlated with the density of the nitrogen vacancies determined by electron spin resonance. Furthermore, the value of n is approximately 1 for 50 μ s to 0.01 s and 0.3 for 1–1000 s. Thus, the luminescence mechanism of Eu 2+ can be discussed by comparing n and τ B obtained from the decay curves. In addition, several different Eu 2+ -doped phosphors, namely SrAl 2 O 4 :Eu 2+ , Dy 3+ , CaAlSiN 3 :Eu 2+ , and CaS:Eu 2+ , Tm 3+ , are studied.