Phase transition, morphology transformation and highly enhanced luminescence properties of YOF:Eu3+ crystals by Gd3+ doping.

A series of undoped and Eu3+ doped YOF and Y1−xGdxOF (x = 0–0.7) crystals were prepared via a urea based homogeneous precipitation method followed by a heat treatment process. After Gd3+ doping, we observed the crystal phase transition, morphology transformation, and greatly enhanced luminescence properties of the YOF crystals. The results reveal that the addition of Gd3+ can promote the phase transition from the hexagonal phase to the rhombohedral phase and the morphology transformation from spheres, though a mixture of rods and spheres, to spheres. The luminescence properties of Eu3+ doped YOF phosphors were investigated upon UV excitation and the quenching concentration of Eu3+ was found to be 10 mol%. More importantly, the luminescence intensity after doping a certain amount of Gd3+ increased by 31 times compared to that of the Gd3+ free sample, which may be due to the modification of the crystal field and the crystal phase of YOF, providing an effective way to gain numerous Gd3+ doped luminescent materials. These results show that the Gd3+ doped red phosphors have potential applications in white light emitting diodes. [ABSTRACT FROM AUTHOR]