Synthesis and optical properties of Gd4Al2O9:Eu3+, a red emitting phosphor with a strong negative thermal quenching effect

Abstract

For the purpose of obtaining red-light phosphors with excellent luminescence thermal stability, a series of Gd₄Al₂O₉:Eu³⁺ (GAO:Eu³⁺) phosphors were synthesized by combining the sol-gel method with high-temperature calcination, and a detailed series of study and analysis of their room temperature and high temperature luminescence properties was carried out. In GAO, the emission peaks corresponding to the ⁵D₀ → ⁷F_j (j = 0, 1, 2, 3 and 4) transitions of Eu³⁺ were observed at 578, 590, 610, 654, and 707 nm, with the strongest emission peak at 610 nm, and the obtained samples were red-light phosphors. The sample GAO:Eu³⁺ synthesized by combining the sol-gel method with high-temperature calcination has a negative thermal quenching (NTQ) effect, and the best doped sample GAO:0.16Eu³⁺ has an optimal luminescence temperature of 120 °C, and the corresponding integrated PL intensity is 183.2% of the initial value at 30 °C. The presence of the NTQ effect makes GAO:0.16Eu³⁺ have good luminescence thermal stability, which manifests as thermal-optical energy conversion at the macroscopic level. A detailed study of the thermal quenching mechanism was carried out.