The excitation spectra of GdNbO _ 4: EU ~ (3 +) phosphors monitored at 610 nm include broad band and sharp peaks, as shown in Fig. 7-2. The former has both charge transfer CTA and NB with NbO43- group. ←-0 °. →Migration. The latter is the 4f forbidden transition of Eu't in GdNbO4 matrix. The two strong peaks are located at near UV 394nm and blue 464nm respectively, which indicates that the GdNbO4: EU + phosphors are suitable for commercial LED. There are two strong emission peaks in the emission spectrum: the strongest peak at 612 nm is the electric dipole transition and the second strong peak at 593 nm is the magnetic dipole transition. The intensity ratio of these two emission peaks is 4.6: 1, and the intensity of electric dipole transition is significantly higher than that of magnetic dipole transition, which indicates that EU replaces GDT in GdNbO4 matrix and occupies the lattice position of non-inversion symmetry center. The spectra of GdNbO2: Eu3 phosphor show that the phosphor can emit high intensity red light effectively by blue light and near ultraviolet light.
Effect of EU ~ (3 +) doping concentration on luminescence intensity of GdNbO _ 4: EU ~ (3 +) Phosphors the luminescence intensity of GdNbO _ 4: EU ~ (3 +) phosphors increases with the increase of Eu't concentration, and the luminescence intensity decreases with the increase of EU ~ (3 +) concentration and the increase of EU ~ (3 +) concentration. This is caused by the concentration quenching caused by EU ~ (3 +) supersaturation in the luminescent center, and the mechanism is generally considered as follows: first, the EU itself is quenched by cross-relaxation (eross relaxation); second, the increase of EU ~ (3 +) concentration accelerates the increase of EU ~ (3 +) concentration.
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