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

An application manner of Judd-Ofelt (J-O) theory to a luminescent powder is studied by exemplifying an Er3+-doped Li 5 La 3 Nb 2 O 12 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 4I 15/2 ↔4I 13/2 (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 Ω i (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 4I 15/2 ↔4I 13/2 one, must be included in the J-O fit. The relative ratios between Ω i 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 Ω i values, and hence restricts the application manner of the related approach. A more reliable application manner of the approach is proposed. • Ω i are determined mainly by strong and medium-intensity transitions. • 1.5 μm transition affects Ω 4 and Ω 6 strongly, it must be included in J-O fit. • Ω i shows a linear relationship to integrated absorption cross-section. • Ω 4 /Ω 2 and Ω 6 /Ω 2 change remarkably with the relative absorption cross-section. • A more convincing and reliable method for calibration of Ω i has been suggested. [ABSTRACT FROM AUTHOR]