Low-temperature And Simple Preparation Of Luminescent Material For Laser Lighting

High-power laser lighting is a brand new lighting technology,because of its advantages of ultra-high lighting,long range,good collimation and high luminous efficiency.It is a new generation of lighting technology after light-emitting diode（LED）lighting.The yellow fluorescent conversion material Y₃Al₅O₁₂:Ce（YAG:Ce）is suitable for blue laser diode（LD）lighting,has high efficiency,and is easy to obtain white light.It is still the most widely studied object at present.However,traditional epoxy resin/organic silicone encapsulated phosphors have low thermal conductivity,which cannot avoid problems such as ablation,blackening,and failure of the fluorescent packaging material under laser excitation.In the future,Using phosphors in ceramic（PICs）instead of traditional luminescent silicone or resin packaging as color converters,which is considered to be an effective way to improve the thermal stability of laser lighting.And the preparation of fluorescent ceramics mostly needs high temperature,high pressure,high vacuum and other conditions,expensive equipment,complicated technology,harsh experimental conditions,it is difficult to popularize.This project proposes more simple and convenient methods to prepare phosphors and fluorescent ceramics.Firstly,using urea as fuel and citric acid as a complexing agent,a yellow luminescent YAG:Ce phosphor was rapidly prepared by solution combustion synthesis（SCS）.The molar ratio of urea to oxidant was studied in detail（Φ）,The effect of the amount of citric acid added on the composition,microscopic morphology,and optical properties of phosphors.Through XRD and SEM analysisΦ=2.3.The addition amount of citric acid is 0.5g,without annealing treatment.Nanocrystalline powder is obtained through combustion reaction in one step,with fine and uniform grains（～80nm）;By analyzing photoluminescence spectroscopy,quantum yield,and fluorescence lifetime,the prepared nano-phosphors exhibit the broadband visible luminescence characteristics and excellent luminescence properties of YAG:Ce.This method quickly synthesized nano-phosphors with uniform composition and structure and good performance through simple processes and equipment,providing a new and more convenient way for the preparation of YAG:Ce powder.Secondly,it is proposed to prepare YAG:Ce-Ca F₂composite fluorescent ceramics by Cold Sintering Process（CSP）,which is composed of YAG:Ce powder particles embedded in a Ca F₂thermal conductive matrix.Fluorescent ceramics with excellent luminescent properties were successfully prepared at temperatures below 500℃.After optimization of experimental conditions and parameters,the YAG:Ce-Ca F₂composite fluorescent ceramic prepared has a relative density of more than 95%,good thermal stability,and a loss of only4.3%in luminous intensity at 400K.It can withstand blue laser irradiation with a power density of 5W/mm²,and achieve high brightness white laser lighting with a luminous flux of910.7lm and a lumen efficiency of 97.55lm/W.