Study on an application manner of Judd-Ofelt theory to a phosphor material

Abstract

Abstract An application manner of Judd-Ofelt (J-O) theory to a luminescent powder is studied by exemplifying an Er3+-doped Li5La3Nb2O12 nanophosphor, on which J-O analysis has been performed previously using the approach based on measured relative absorption (optical density) spectrum and Er3+ 1.5 μm fluorescence lifetime. Present study focuses on two key issues that are closely related to the reliability and application manner of the approach but not clarified in the previous study. First, whether or not a strong or medium-intensity oscillator, such as the 4I15/2↔4I13/2 (1.5 μm) one, can be excluded from the J-O least-square fit. Second, whether the relative ratio between the J-O intensity parameters Ωi (i = 2, 4, 6) remains unchanged as the integrated optical densities (IODs) of all transitions change all together by a factor x. Our studies show that the strong or medium-intensity transition oscillator, such as the 4I15/2↔4I13/2 one, must be included in the J-O fit. The relative ratios between Ωi change remarkably with the collectively varying factor x of the IODs for smaller x values because of magnetic dipole contribution of the 1.5 μm oscillator. The change is undesired as it may result in the deviation of Ωi values, and hence restricts the application manner of the related approach. A more reliable application manner of the approach is proposed.