Preparation And Up-conversion Luminescence Properties Of Na₂O-Y₂O₃-P₂O₅-SiO₂ Glass-ceramics

Rare earth ions doped in different matrix materials can form a variety of luminescent materials.At present,rare earth luminescent materials play an important role in white LED lighting,flat panel display,photoelectric detection and other fields.Na₂O-Y₂O₃-P₂O₅-SiO₂ glass-ceramics prepared by the melting-crystallization method is one of the excellent matrix materials for rare earth upconversion luminescence.Phosphate crystal phases are uniformly distributed in the oxide glass network of the glass-ceramics,which not only has high chemical stability and mechanical strength of the oxide glass-ceramics,but also has high luminescence efficiency and intensity of rare earth ions in the phosphate matrix.Therefore,it is of great significance to study the preparation and upconversion luminescence properties of rare earth doped Na₂O-Y₂O₃-P₂O₅-SiO₂ glass-ceramics.The formula of precursor glass was optimized by orthogonal test,and the optimum composition of Na₂O-Y₂O₃-P₂O₅-SiO₂ precursor glass was determined.Tb³⁺-Yb³⁺,Ho³⁺-Yb³⁺and Er³⁺-Yb³⁺co-doped containing Na_3.6Y_1.8?PO₄?₃ crystalline phases phosphosilicate glass-ceramics were prepared by melting-crystallization method.By discussing the effects of heat treatment temperature and time on the average grain size,crystallinity,grain distribution and transmittance of glass-ceramics samples,the optimum heat treatment conditions of Tb³⁺-Yb³⁺,Ho³⁺-Yb³⁺and Er³⁺-Yb³⁺co-doped phosphosilicate glass-ceramics containing Na_3.6Y_1.8?PO₄?₃crystalline phase were determined to be 645?for 180 min,665?for 240 min and630?for 120 min,respectively?Comparing the microstructures of Na2O-Y2O3-P2O5-SiO2 precursor glasses and glass-ceramics samples,the up-conversion luminescence intensity and quantum field of glass-ceramics are enhanced due to the formation of phosphate groups in glass-ceramics samples.The influence of doping concentration of Tb₄O₇ and Ho₂O₃on the upconversion luminescence intensity of phosphosilicate glass-ceramics was discussed.The optimum doping concentration of Tb₄O₇ and Ho₂O₃ was determined to be 0.4 mol%.The up-conversion luminescence intensity and quantum field of glass-ceramics samples with different doping concentration ratios of Tb₄O₇/Yb₂O₃,Ho₂O₃/Yb₂O₃ and Er₂O₃/Yb₂O₃ were discussed,and the optimum doping concentration ratios were determined to be 2:5,1:2 and 1:7,respectively.It is determined that the upconversion radiation of Tb³⁺,Ho³⁺and Er³⁺ions is a two-photon process.The chromaticity coordinates of upconversion luminescence of Tb³⁺-Yb³⁺,Ho³⁺-Yb³⁺and Er³⁺-Yb³⁺co-doped glass-ceramics were calculated,Tb³⁺-Yb³⁺and Ho³⁺-Yb³⁺doped glass-ceramics was in green region,and that of Er³⁺-Yb³⁺doped glass-ceramics was in blue-green region.The quantitative relationship between the microstructure and light transmittance of phosphosilicate glass ceramics was studied by stereology theory.With the increase of the DS,the light transmittance is decreased gradually.As the increases of the SV,the transmittance decreases.With the increase of SVP,the transmittance of light is increased.The light transmittance is increased with the increase of?.Therefore,the crystal morphology,grain radius and the distance between the grains determine the transmittance of the glass ceramic sample.The phase transition temperature of phosphosilicate glass-ceramics was obtained by differential scanning calorimetry.The relationship between superheat and the number of critical nuclei was explained by nucleation thermodynamics theory.The results show that the smaller the superheat,the smaller the number of critical nuclei.Fractal dimension of phosphosilicate transparent glass-ceramics was calculated by box dimension method.The grain growth has fractal characteristics.The crystal growth process of phosphosilicate glass-ceramics was analyzed by fractal dynamics theory,and the relationship between the kinetic parameter h and the percentage of crystal area was established.The dynamic parameters h of Er³⁺-Yb³⁺,Tb³⁺-Yb³⁺and Ho³⁺-Yb³⁺doped phosphosilicate glass-ceramics were obtained by linear fitting.The fractal sub-spectral dimensions dS were calculated to be 1.029,1.045 and 1.129,respectively.