Preparation And Characterization Of Dy³⁺ Doped Fluoride Borate Glass Phosphors For Laser Illumination

Rare earth elements are one of the indispensable materials for the synthesis of laser lighting materials.The white light source excited by semiconductor laser has the advantages of small volume,low energy consumption,high brightness,high luminous efficiency and stable light color.It is a new generation of solid state lighting source with strong plasticity.For semiconductor laser source of white light,a series of Dy³⁺doped NCZLB fluoroborate glass phosphor samples synthesized by the high temperature melting method,and the fluorescent properties of the samples excited at different wavelengths were studied,and this work has attempted to optimize the size of the glass phosphor and the concentration of doped rare earth ions,that achieved the desired white-light emission.The color coordinates were calculated under the blue phosphor excitation laser pumped,and the 1931-CIE diagrams show the moving trend of the color coordinates with varying excitation wavelength.This work lays a foundation for the research of high quality combination white light solid lighting equipment.The results of this work are as follows:1.According to the glass molar composition of 25Na₂O-19CaF₂-8ZnO-8La₂O₃-40B₂O₃,NCZLB fluoroborate optical glasses were prepared by high temperature melting method.In additional,the rare earth ions were introduced with high purity oxide Dy₂O_3,and the doping concentrations were 0.02wt%,0.05wt%,0.50wt%,1.00wt%,1.50wt%and 2.00wt%Dy₂O₃,respectively.Through the test and analysis of the refractive index,XRD and DTA of the samples,the glass material has good transparency and the glass synthesis process is in good condition,the thermal stability range of the glass is about 150 centigrade,and has good thermal stability and anti-crystallization ability.2.Under the excitation of xenon lamp with wavelength of 350nm and 388nm,the emission spectra of Dy³⁺doped NCZLB fluorosilicate glasses were obtained.the three emission peaks of the Dy³⁺doped NCZLB glasses are located at 483,575 and 664nm,respectively,and the corresponding transition emission was attributed to ⁴F_9/2?⁶H_15/2,⁴F_9/2?⁶H_13/2 and ⁴F_9/2?⁶H_ll/2.Meanwhile,the strongest emission at 575nm of Dy³⁺were monitored,and eight obvious excitation peaks were observed in the wavelength range of200-560nm,the excitation band in the range of 290-480nm further proves that NCZLB fluoroborate fluorite can be applied to white light LD in blue pump.The strong emission peaks of NCZLB fluoroborate glasses doped with Dy³⁺were fitted.It was found that the quenching mechanism of Dy³⁺concentration in NCZLB fluoroborate glasses doped with Dy³⁺should be the interaction between electric dipole and electric dipole,and the optimum doping concentration was between 1.00wt%and 2.00wt%.3.According to Judd-Ofelt theory,through the analysis of the absorption spectra of Dy³⁺doped NCZLB fluoroborate glass,the J-O intensity parameters?_t?t=2,4,6?of Dy³⁺in NCZLB fluoroborate glass calculated to be 5.48?10^-20,1.85?10^-20 and 1.45?10^-20cm²,respectively,the larger?₂ indicates that Dy³⁺doped NCZLB fluoroborate glass has strong covalent and asymmetry.Using the intensity parameters?_t values,Using the intensity parameters?_t values,some related radiation spectrum parameters including spontaneous transition probabilities,branching ratios,and radiative lifetime for the optical transitions of Dy³⁺in NCZLB glasses have been calculated.4.The spectral power distributions of fluorescence for 0.20wt%and 1.00wt%Dy₂O₃doped NCZLB glasses were obtained using an integrating sphere connected with a 453nm blue laser pumping source,the net emission photon number and the quantum yields are identified.The total quantum yields of 0.20wt%and 1.00wt%Dy₂O₃ doped NCZLB glasses reach 10²6%,indicating that effectiveness of the warm yellowish-white luminescence in Dy³⁺doped fluoroborate glass fluorescein.and further demonstrating the potential of Dy³⁺doped NCZLB glass phosphor as excellent laser illumination source.5.In order to achieve the desired white-light emission,large-sized Dy.³⁺doped NCZLB glasses A and B for 1.00wt%and 1.50wt%cases were synthesized to optimize the doping concentration of rare earth ions and the size of the phosphor.Under the excitation of 453nm blue laser with different powers,fluorescent color coordinates are located in the white light region,and obvious photoluminescent improvement of Dy³⁺emissions was observed with the increase of the rare earth ions and the size of the phosphor.For example,under the pumped laser excitation of the 56mW excitation power,the color coordinates of the phosphor A are moved from the point?0.282,0.229?to the warm white light point?0.316,0.288?,and the corresponding luminous flux increased from 1.56lm to 9.07ml.The efficient and adjustable white light show that the Dy³⁺doped NCZLB fluoride borate glass phosphor has a good application prospect in the field of laser lighting.