Preparation Of CaO Transparent Ceramics And Study On Luminescence Properties Of Rare Earth Doping

With the development of lighting technology,traditional lighting methods with high energy consumption and high pollution（mercury lamps）are gradually being eliminated,while high-efficiency,environmental protection,and energy-saving lighting devices will occupy a dominant position in the current and future development.At present,in the field of lighting,high-power LED and laser lighting,which are at the forefront of lighting technology,have become research hotspots.Under the high-density heat generated under high-power LED or laser lighting conditions,organic resins,silica gel,etc.can hardly withstand the thermal attack generated by high-power LED/LD light sources,and are prone to aging,resulting in fluorescence quenching,color drift,and luminous efficiency decline.And other problems,the traditional phosphor powder mixed glue packaging form is facing more severe challenges.In recent years,fluorescent ceramic materials with excellent thermal stability and luminescence properties have been extensively studied and become one of the fluorescent conversion materials for high-power LEDs and lasers.Among them,YAG:Ce is used as the yellow light fluorescent material of traditional white light LEDs.Due to the lack of red light,YAG:Ce transparent ceramics have shortcomings such as high color temperature（CCT）and low color rendering index（Ra）in white light LED performance.To this end,a CaO transparent ceramic material was developed in this paper,and a CaO:Ce fluorescent ceramic material with high color rendering performance was prepared by doping CaO with Ce³⁺.This article describes the preparation process in detail and systematically studies the related material properties,fluorescent properties and luminescent properties of the packaged light source.The main research conclusions of this paper are as follows:（1）CaO transparent ceramics were successfully prepared by using YF₃ as a sintering aid.The sample sintered at 1350℃ has the highest relative density,reaching99.71%,the in-line transmittance at 1200 nm wavelength reaches 47.10%,and the thermal conductivity reaches 15.42 W/（m K）at 25℃.In addition,the hydrolysis resistance is greatly enhanced due to the non-porous dense structure.Compared with CaO ceramics with a relative density of 78.66%,the hydrolysis-induced weight gain of S1350 decreased significantly from 21.80%to 1.20%within 35 days.（2）A series of high-quality CaO:xCe（x=0.01%,0.03%,0.05%,0.07%）fluorescent ceramics were prepared with 0.5 mol%Al₂O₃ as a sintering aid.Compared with YF₃ sintering aid,the thermal conductivity of CaO:Ce fluorescent ceramics with Al₂O₃ as sintering aid is higher,reaching 26.8 W/（m K）,and in the 35-day weight gain experiment,its mass An increase of less than 1.5%.We tested the fluorescent properties of the system fluorescent ceramics.Excite CaO:Ce fluorescent ceramics with an excitation wavelength of 460 nm to obtain a broad emission spectrum close to the peak of 580 nm,with a spectral half-maximum width of 152 nm,sufficient red light components,and a fluorescence lifetime of about 66 ns,with the highest quantum efficiency QY reaching 97.9%.These performance test results show that CaO:Ce fluorescent ceramic materials can meet the needs of white LED/LD light sources with high color rendering performance.（3）The prepared CaO:0.01%Ce fluorescent ceramic package was tested on a 460nm high-power COB blue light integrated chip to test its LED performance.When the electric power was 2.1 W and the current was 100 m A,the color coordinates were（0.3222,0.3199）white LED light source,the color temperature is 6038 K,compared with the traditional YAG:Ce,the color rendering index is increased to 83.In addition,this paper studies the luminous performance of the reflective laser illumination source encapsulated by CaO:xCe fluorescent ceramics.It is found that CaO:Ce fluorescent ceramics have better high-temperature luminescence properties than YAG:Ce.Under the same conditions,YAG:Ce ceramics reached the saturation threshold of thermoluminescence at 23.678 W/mm²,and the luminous flux was 2360.79 lm.When the laser power density of CaO:0.03%Ce was 34.058 W/mm²,the luminous flux reached the highest 4141 lm.