Yellow-light emitting Tb3Al5O12:Ce3+ phosphor properties sensitized by Bi3+ ions

Abstract A new yellow-light emitting garnet phosphor Tb 3 Al 5 O 12 :Ce 3+ , Bi 3+ (TAG:Ce 3+ , Bi 3+ ) was synthesized by the metal organic decomposition method. The phosphor properties with different Ce 3+ /Bi 3+ dopant concentrations were studied in detail using X-ray diffraction (XRD) analysis, photoluminescence (PL) and PL excitation spectroscopies, and diffuse reflectance measurements. The optimum concentrations of Ce 3+ /Bi 3+ deduced from the PL intensity measurements by excitation at λ ex = 325 nm were ∼ 0.2 mol% (Ce 3+ and Bi 3+ ). The addition of Bi 3+ ions into the Ce 3+ singly doped phosphor increased ∼ 43% of the PL intensity. The XRD data further suggested an improvement in the crystalline quality of the Ce 3+ singly doped phosphor by codoping with Bi 3+ . An increase in the PL intensity was attributed to an energy transfer from Tb 3+ to Bi 3+ and Ce 3+ together with an improved crystalline quality of the (Ce 3+ , Bi 3+ )-codoped phosphor. Temperature dependence of the luminescence intensities was also measured at T = 20–500 K in 10-K increments and analyzed using the conventional model with thermal quenching energies of E q1 = 35 meV and E q2 = 0.40 eV. The experimental data for the Ce 3+ singly doped phosphor, however, required an additional term of trap states with energy of E t = 3 meV, in agreement with poor crystalline quality of the TAG:Ce 3+ phosphor.