Photoluminescent and cathodoluminescent performances of Tb3+ in Lu3+-stabilized gadolinium aluminate garnet solid-solutions of [(Gd1−xLux)1−yTby]3Al5O12

Abstract

A series of [(Gd_1−xLu_x)_1−yTb_y]₃Al₅O₁₂ green phosphors have been calcined from their coprecipitated carbonate precursors. Increasing Lu³⁺ incorporation was found to significantly simplify the reaction pathway and lower the temperature of garnet formation, and at the same time leads to contracted cell dimensions and improved theoretical density. Photoluminescent properties, in terms of excitation, emission, concentration quenching, quantum yield, color coordinates of emission, efficiency of excitation absorption, fluorescence decay, and relative intensity of the ⁵D₄ → ⁵F₆/⁵D₄ → ⁵F₅ emissions, are thoroughly investigated against the Lu and Tb contents, temperature of the phosphor synthesis, and electronegativity of the cations in the host lattice. The best luminescent [(Gd_0.8Lu_0.2)_0.9Tb_0.1]AG combination exhibits photoluminescence very close to (Y_0.9Tb_0.1)AG and significantly better than (Lu_0.9Tb_0.1)AG. Cathodoluminescence found that the [(Gd_0.8Lu_0.2)_0.9Tb_0.1]AG phosphor is structurally stable in the range of this study, and exhibits successively higher emission brightness by increasing either the acceleration voltage (up to 6 kV) or beam current (up to 55 μA). The high density green phosphor developed in this work may find lighting, display, and scintillation applications.