Solvothermal synthesis and luminescence properties of Tb3+-doped gadolinium aluminum garnet

Different concentrations of Tb3+ ion-doped gadolinium aluminum garnet (GAG) nanophosphors have been synthesized by solvothermal reaction method and sintered at 1300 °C. The XRD patterns confirm that the GAG phosphors sintered at 1300 °C have a garnet structure with single cubic phase. The calculated crystallite size is about 92 nm. The SEM images of the phosphors show the spherical morphology agglomerated with many small particles. The luminescence properties of these phosphors have been carried out by the emission and excitation spectra along with lifetime measurements. The excitation spectra of GAG:Tb3+ phosphors consist of three broad bands due to the 4f8→4f75d1 transition and some sharp peaks due to the 4f8→4f8 transition. The emission spectra of the phosphors reveal two colors, such as blue due to 5D3→7FJ transitions and green due to the 5D4→7FJ transitions. The dynamics of the phosphors have been investigated by decay curves and the cross-relaxation process and is observed at 0.5 mol% Tb3+ concentration.