Spectral and thermal properties of Dy3+-doped NaGdTiO4 phosphors

Dy3+-doped NaGdTiO4 phosphors were synthesized by a solid-state reaction method. The crystal structure, spectral properties and fluorescence quenching of the phosphors were systematically studied by means of X-ray diffraction (XRD) and spectroscopy. It was found that the phosphors can be effectively excited by 281 nm ultraviolet light, and intense white light emission was observed. The white light was generated by mixing blue (483 nm) and yellow (578 nm) emissions corresponding to the transitions from F-4(9/2) to H-6(15/2) and H-6(13/2) levels of Dy3+. The electric dipole-dipole interaction between Dy3+ ions was identified as the main mechanism for the concentration dependent fluorescence quenching of 4F9/2 level. The CIE color coordinates of the phosphors were calculated to be (x = 0.3345, y = 0.3535) in the white region under 281 nm excitation, which is very close to the E point (energy equal point, x = 0.3333, y = 0.3333). In addition, the thermal quenching behavior of F-4(9/2) level of Dy3+ was also discussed, and the crossover effect was confirmed to be the dominant physical mechanism responsible for the fluorescence temperature quenching of Dy3+ in NaGdTiO4 host. (C) 2011 Elsevier B.V. All rights reserved.