Preparation And Luminescence Properties Of Dy³⁺/Sm³⁺ Doped Na₃Gd（PO₄）₂ Crystalline Glass Ceramics

Traditional commercial white light-emitting diode（W-LED）has some disadvantages such as low color rendering index,short fluorescence life and environmental pollution.In order to find a good alternative to W-LED,people continue to explore.Rare earth doped glass ceramics with good sealing,high color index and environmental protection and other advantages have been found.In this paper,Dy³⁺doped,Sm³⁺doped and Dy³⁺/Sm³⁺doped Na₃Gd（PO₄）₂ crystal phase glass ceramics were prepared by melt-crystallization method.The glass ceramics were tested by X-ray diffraction.It can be confirmed that the glass ceramics contains Na₃Gd（PO₄）₂ crystal phase because all of the diffraction peaks of the glass ceramics are well matched with standard PDF card.Combined with differential scanning calorimetry,X-ray diffraction,electron microscope photographs and transmittance curves,the optimal heat treatment condition for Dy³⁺doped,Sm³⁺doped and Dy³⁺/Sm³⁺co-doped glass ceramics were determined to be 660℃/2 h,650℃/2 h and 640℃/2 h,respectively.Under the optimal heat treatment condition,the transmittance of glass-ceramic samples in visible light range were 76.5%,82.5%and 77.5%,respectively,and the grains distribution in the glass ceramics is uniform by scanning electron microscope photographs.The luminescence properties of Dy³⁺,Sm³⁺and Dy³⁺/Sm³⁺doped glass ceramics at different doping concentrations were studied by excitation spectra and emission spectra.The optimum doping concentration of Dy₂O₃ doped,Sm₂O₃doped and Dy₂O₃/Sm₂O₃doped glass ceramics were 0.7%,0.8%and 0.7%-0.8%,respectively.The critical distance of Dy³⁺doped,Sm³⁺doped and Dy³⁺/Sm³⁺co-doped glass ceramics samples were calculated.The energy transfer between Dy³⁺and Sm³⁺was found by analyzing the emission spectra and fluorescence lifetime of Dy³⁺/Sm³⁺doped glass ceramic samples,and the energy transfer efficiency of Dy³⁺to Sm³⁺was calculated.Further analysis revealed that the energy transfer from Dy³⁺to Sm³⁺followed dipole-quadrupole interaction.The chromaticity coordinate analysis of Dy³⁺/Sm³⁺co-doped glass ceramics shows that the chromaticity coordinate value of 0.7%Dy₂O₃-0.8%Sm₂O₃ doped glass ceramics is close to the white light region.This indicates that Dy³⁺/Sm³⁺doped Na₃Gd（PO₄）₂ crystalline glass ceramics has potential application value in the field of white light-emitting diode（W-LED）.