Fluorescence quenching of 5DJ (J=1, 2 and 3) levels and Judd-Ofelt analysis of Eu3+ in NaGdTiO4 phosphors

NaGdTiO4 phosphors with various Eu3+ concentrations were synthesized by a solid-state reaction. The crystal structure and fluorescence properties were characterized by means of x-ray diffraction and fluorospectroscopy, respectively. An effective energy transfer from the titanate matrix to the activator Eu3+ was observed. An intense red emission originating from D-5(0) -> F-7(2) of Eu3+ was observed while excited at the TiO44- charge transfer bands or f-f absorption bands of Eu3+. The fluorescence quenching of D-5(J) (J = 1, 2 and 3) levels were studied based on the Van Uitert model. Electric dipole-dipole interaction was confirmed to be the main mechanism of the fluorescence quenching of D-5(J) levels, which is responsible for the cross-relaxation between Eu3+ ions. The full optical transition intensity parameters Omega(lambda) (lambda = 2, 4, 6) of Eu3+ in the NaGdTiO4 phosphors were calculated in the framework of Judd-Ofelt theory to be 6.024 x 10(-20), 1.512 x 10(-20) and 0.374 x 10(-20) cm(2).