Ba5Zn4Gd8O21:Tb3+—structural characterization and the judd-ofelt parameterization from emission spectra

Ba5Zn4Gd8O21:Tb3+ nanorods; synthesized via solution combustion route; were found to crystallize in the tetragonal (I4/m, 87) crystal system. The UV excitation at 290 nm of all Ba5Zn4Gd8O21:Tb3+ samples yielded the characteristics emission corresponding to 5D4 → 7F6,5,4,3 transitions in Tb3+ activator (used for Judd-Ofelt analysis). A detailed investigation of photoluminescence decay curves and emission spectra of Ba5Zn4Gd8O21:Tb3+ nanorods provided the radiative lifetime (1.0889 ms) and total radiative transition rates from 5D4 state in Tb3+ ion. The electric-dipole radiative transition probabilities (extracted from total radiative rates i.e electric-dipole + magnetic-dipole) were used to calculate the Judd–Ofelt intensity parameters (Ω2 = 4.76×10−20, Ω4 = 2.11×10−20 and Ω6 = 2.00×10−20 cm2). The very high quantum efficiency of 5D4 state (81%) suggests their potential use in lighting and display devices. Finally, a large magnitude of peak stimulated emission cross section of 5D4 → 7F5 (16.5838×10−20 cm2) transition also claims their promising candidature as a good laser material.