Preparation And Luminescence Properties Of Dy³⁺ And Sm³⁺ Doped Transparent Glass-ceramics Containing NaGd（MoO₄）₂

In the field of LEDs,transparent glass ceramics have potential applications and research value because of their advantages such as high thermal stability,high energy efficiency and long luminescence life compared with phosphors.In this thesis,transparent glass ceramics containing Na Gd（MoO₄）₂ crystalline phase were successfully prepared by the melt-curing-crystallization method with Dy³⁺single-doped,Sm³⁺single-doped,and Dy³⁺-Sm³⁺double-doped,and their microscopic morphology,luminescence performance,and energy transfer mode were investigated in depth.The required raw materials for the Na Gd（MoO₄）₂ crystalline phase glass-ceramics were determined by reviewing the literature,and the formulation was optimized according to the controlled variable method to determine the percentage composition of the amount of substance.The optimal heat treatment conditions for Dy³⁺single-doped,Sm³⁺single-doped,and Dy³⁺-Sm³⁺double-doped glass ceramics were determined by using differential scanning calorimetry（DSC）to select the temperature range of heat treatment,X-ray diffraction（XRD）combined with scanning electron microscopy（SEM）and optical transmittance curves to determine the optimal heat treatment conditions of 650℃/1.5 h,630℃/2 h and 670℃/2 h;the optical transmittance was 79%,80%and 83%,respectively.Based on the excitation spectra and emission spectra of Dy³⁺single-doped,Sm³⁺single-doped,and Dy³⁺-Sm³⁺double-doped glass ceramics,the optimal doping concentrations of 1.2%Dy³⁺,0.7%Sm³⁺,and 1.2%Dy³⁺-1.3%Sm³⁺were determined for the three systems of glass ceramics,respectively.By calculating the critical distance（R_c）,it was determined that the main reason for the concentration burst occurring in the three systems of glass ceramics was the electric multipole interaction;by analyzing the fluorescence lifetime curves,it was determined that there was energy transfer from Dy³⁺to Sm³⁺by the mechanism of dipole-quadrupole interaction,and the energy transfer efficiency was calculated.By analyzing the chromaticity coordinates of the double-doped glass-ceramics,the addition of Sm³⁺provides the red light component for the Dy³⁺single-doped glass-ceramics to achieve warm white light emission with a color temperature of 3641 K.And by continuing to increase the doping concentration of Sm³⁺in the double-doped system,the adjustable emission from cold white light to red light can be achieved.Taken together,the above analysis indicates that Dy³⁺-Sm³⁺double-doped glass ceramics are valuable for research in the field of white LEDs.